diff --git a/CMakeLists.txt b/CMakeLists.txt
index b231d7a81a..f34c95e06a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.2)
 project(TogglDesktop)
 
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
 
 # Set up automatic resource generation to make Qt development easier
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index c11aba3162..09b48d0db0 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -33,6 +33,9 @@ include_directories(
 
 # TogglDesktopLibrary sources
 set(LIBRARY_SOURCE_FILES
+    util/logger.cc
+    util/error.cc
+
     base_model.cc
     batch_update_result.cc
     client.cc
@@ -48,7 +51,6 @@ set(LIBRARY_SOURCE_FILES
     feedback.cc
     formatter.cc
     get_focused_window_linux.cc
-    error.cc
     gui.cc
     netconf.cc
     https_client.cc
diff --git a/src/analytics.cc b/src/analytics.cc
index 96d08622f0..ba9adef70a 100644
--- a/src/analytics.cc
+++ b/src/analytics.cc
@@ -17,8 +17,7 @@
 #include "settings.h"
 #include "urls.h"
 #include "user.h"
-
-#include <Poco/Logger.h>
+#include "util/logger.h"
 
 namespace toggl {
 
@@ -162,7 +161,7 @@ void GoogleAnalyticsEvent::runTask() {
     HTTPSClient client;
     HTTPSResponse resp = client.Get(req);
     if (resp.err != noError) {
-        Poco::Logger::get("Analytics").error(resp.err);
+        Logger("Analytics").error(resp.err);
         return;
     }
 }
@@ -319,7 +318,7 @@ void GoogleAnalyticsSettingsEvent::makeReq() {
     HTTPSClient client;
     HTTPSResponse resp = client.Get(req);
     if (resp.err != noError) {
-        Poco::Logger::get("Analytics").error(resp.err);
+        Logger("Analytics").error(resp.err);
         return;
     }
 }
diff --git a/src/base_model.cc b/src/base_model.cc
index 93e87394e4..236e0a980f 100644
--- a/src/base_model.cc
+++ b/src/base_model.cc
@@ -12,7 +12,6 @@
 #include <Poco/Timestamp.h>
 #include <Poco/DateTime.h>
 #include <Poco/LocalDateTime.h>
-#include <Poco/Logger.h>
 
 namespace toggl {
 
@@ -22,8 +21,7 @@ bool BaseModel::NeedsPush() const {
     // pushed again unless the error is somehow fixed by user.
     // We will assume that if user modifies the model, the error
     // will go away. But until then, don't push the errored data.
-    return ValidationError().empty() &&
-           (NeedsPOST() || NeedsPUT() || NeedsDELETE());
+    return ValidationError() == noError && (NeedsPOST() || NeedsPUT() || NeedsDELETE());
 }
 
 bool BaseModel::NeedsPOST() const {
@@ -56,7 +54,7 @@ void BaseModel::ClearValidationError() {
     SetValidationError(noError);
 }
 
-void BaseModel::SetValidationError(const std::string &value) {
+void BaseModel::SetValidationError(const error &value) {
     if (validation_error_ != value) {
         validation_error_ = value;
         SetDirty();
@@ -113,7 +111,7 @@ error BaseModel::LoadFromDataString(const std::string &data_string) {
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(data_string, root)) {
-        return error("Failed to parse data string");
+        return error(error::kFailedToParseData);
     }
     LoadFromJSON(root["data"]);
     return noError;
@@ -154,8 +152,7 @@ error BaseModel::ApplyBatchUpdateResult(
 }
 
 bool BaseModel::userCannotAccessWorkspace(const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        kCannotAccessWorkspaceError));
+    return err == error::kCannotAccessWorkspaceError;
 }
 
 std::string BaseModel::batchUpdateRelativeURL() const {
@@ -183,7 +180,7 @@ std::string BaseModel::batchUpdateMethod() const {
 // Convert model JSON into batch update format.
 error BaseModel::BatchUpdateJSON(Json::Value *result) const {
     if (GUID().empty()) {
-        return error("Cannot export model to batch update without a GUID");
+        return error::kExportWithoutGUID;
     }
 
     Json::Value body;
@@ -197,8 +194,8 @@ error BaseModel::BatchUpdateJSON(Json::Value *result) const {
     return noError;
 }
 
-Poco::Logger &BaseModel::logger() const {
-    return Poco::Logger::get(ModelName());
+Logger BaseModel::logger() const {
+    return { ModelName() };
 }
 
 void BaseModel::SetDirty() {
diff --git a/src/base_model.h b/src/base_model.h
index cdf9bb8d32..369cea5ffb 100644
--- a/src/base_model.h
+++ b/src/base_model.h
@@ -12,13 +12,10 @@
 
 #include "const.h"
 #include "types.h"
+#include "util/logger.h"
 
 #include <Poco/Types.h>
 
-namespace Poco {
-class Logger;
-}
-
 namespace toggl {
 
 class BatchUpdateResult;
@@ -35,7 +32,7 @@ class TOGGL_INTERNAL_EXPORT BaseModel {
     , deleted_at_(0)
     , is_marked_as_deleted_on_server_(false)
     , updated_at_(0)
-    , validation_error_("")
+    , validation_error_(error::kNoError)
     , unsynced_(false) {}
 
     virtual ~BaseModel() {}
@@ -122,8 +119,8 @@ class TOGGL_INTERNAL_EXPORT BaseModel {
     void EnsureGUID();
 
     void ClearValidationError();
-    void SetValidationError(const std::string &value);
-    const std::string &ValidationError() const {
+    void SetValidationError(const error &value);
+    const error &ValidationError() const {
         return validation_error_;
     }
 
@@ -156,7 +153,7 @@ class TOGGL_INTERNAL_EXPORT BaseModel {
     error BatchUpdateJSON(Json::Value *result) const;
 
  protected:
-    Poco::Logger &logger() const;
+    Logger logger() const;
 
     bool userCannotAccessWorkspace(const toggl::error &err) const;
 
@@ -176,7 +173,7 @@ class TOGGL_INTERNAL_EXPORT BaseModel {
 
     // If model push to backend results in an error,
     // the error is attached to the model for later inspection.
-    std::string validation_error_;
+    error validation_error_;
 
     // Flag is set only when sync fails.
     // Its for viewing purposes only. It should not
diff --git a/src/batch_update_result.cc b/src/batch_update_result.cc
index de3fe9a191..8f2845e4bc 100644
--- a/src/batch_update_result.cc
+++ b/src/batch_update_result.cc
@@ -7,8 +7,6 @@
 
 #include "base_model.h"
 
-#include <Poco/Logger.h>
-
 namespace toggl {
 
 error BatchUpdateResult::Error() const {
@@ -16,12 +14,12 @@ error BatchUpdateResult::Error() const {
         return noError;
     }
     if ("null" != Body) {
-        return Body;
+        return error::REMOVE_LATER_BATCH_UPDATE_ERROR;
     }
     std::stringstream ss;
     ss  << "Request failed with status code "
         << StatusCode;
-    return ss.str();
+    return error::REMOVE_LATER_BATCH_UPDATE_ERROR;
 }
 
 std::string BatchUpdateResult::String() const {
@@ -56,25 +54,21 @@ void BatchUpdateResult::ProcessResponseArray(
     poco_check_ptr(models);
     poco_check_ptr(errors);
 
-    Poco::Logger &logger = Poco::Logger::get("BatchUpdateResult");
     for (std::vector<BatchUpdateResult>::const_iterator it = results->begin();
             it != results->end();
             ++it) {
         BatchUpdateResult result = *it;
 
-        logger.debug(result.String());
+        logger().debug(result.String());
 
         if (result.GUID.empty()) {
-            logger.error("Batch update result has no GUID");
+            logger().error("Batch update result has no GUID");
             continue;
         }
 
         BaseModel *model = (*models)[result.GUID];
         if (!model) {
-            std::stringstream ss;
-            ss << "Server response includes a model we don't have! GUID="
-               << result.GUID;
-            logger.warning(ss.str());
+            logger().warning("Server response includes a model we don't have! GUID=", result.GUID);
             continue;
         }
         error err = model->ApplyBatchUpdateResult(&result);
@@ -85,27 +79,29 @@ void BatchUpdateResult::ProcessResponseArray(
     }
 }
 
+Logger BatchUpdateResult::logger() {
+    return { "BatchUpdateResult" };
+}
+
 error BatchUpdateResult::ParseResponseArray(
     const std::string &response_body,
     std::vector<BatchUpdateResult> *responses) {
 
     poco_check_ptr(responses);
 
-    Poco::Logger &logger = Poco::Logger::get("BatchUpdateResult");
-
     // There seem to be cases where response body is 0.
     // Must investigate further.
     if (response_body.empty()) {
-        logger.warning("Response is empty!");
+        logger().warning("Response is empty!");
         return noError;
     }
 
-    logger.debug(response_body);
+    logger().debug(response_body);
 
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(response_body, root)) {
-        return error("error parsing batch update response");
+        return error::kFailedToParseData;
     }
 
     for (unsigned int i = 0; i < root.size(); i++) {
diff --git a/src/batch_update_result.h b/src/batch_update_result.h
index f4d9928fad..a99ae68a69 100644
--- a/src/batch_update_result.h
+++ b/src/batch_update_result.h
@@ -8,6 +8,7 @@
 #include <map>
 
 #include "types.h"
+#include "util/logger.h"
 
 #include <json/json.h>  // NOLINT
 
@@ -43,6 +44,10 @@ class TOGGL_INTERNAL_EXPORT BatchUpdateResult {
         std::vector<BatchUpdateResult> * const results,
         std::map<std::string, BaseModel *> *models,
         std::vector<error> *errors);
+
+ private:
+    static Logger logger();
+
 };
 
 }  // namespace toggl
diff --git a/src/client.cc b/src/client.cc
index 5e331c65ba..e4db105481 100644
--- a/src/client.cc
+++ b/src/client.cc
@@ -68,7 +68,7 @@ bool Client::ResolveError(const toggl::error &err) {
         SetName(Name() + " 1");
         return true;
     }
-    if (err.find(kClientNameAlreadyExists) != std::string::npos) {
+    if (err == error::kClientNameAlreadyExists) {
         // remove duplicate from db
         MarkAsDeletedOnServer();
         return true;
@@ -77,13 +77,11 @@ bool Client::ResolveError(const toggl::error &err) {
 }
 
 bool Client::nameHasAlreadyBeenTaken(const error &err) {
-    return (std::string::npos != std::string(err).find(
-        "Name has already been taken"));
+    return err == error::kNameAlreadyTaken;
 }
 
 bool Client::ResourceCannotBeCreated(const toggl::error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "cannot add or edit clients in workspace"));
+    return err == error::kCannotModifyWorkspaceData;
 }
 
 }   // namespace toggl
diff --git a/src/const.h b/src/const.h
index 5c401e2853..5e32b7420f 100644
--- a/src/const.h
+++ b/src/const.h
@@ -45,57 +45,6 @@
 #define kContentTypeMultipartFormData "multipart/form-data"
 #define kContentTypeApplicationJSON "application/json"
 
-// Data validation errors
-#define kOverMaxDurationError "Max allowed duration per 1 time entry is 999 hours"
-#define kMaxTagsPerTimeEntryError "Tags are limited to 50 per task"
-#define kInvalidStartTimeError "Start time year must be between 2006 and 2030"
-#define kInvalidStopTimeError "Stop time year must be between 2006 and 2030"
-#define kInvalidDateError "Date year must be between 2006 and 2030"
-#define kStartNotBeforeStopError "Stop time must be after start time"
-#define kMaximumDescriptionLengthError "Maximum length for description (3000 chars) exceeded"
-
-#define kCheckYourSignupError "Signup failed - please check your details. The e-mail might be already taken."  // NOLINT
-#define kEndpointGoneError "The API endpoint used by this app is gone. Please contact Toggl support!"  // NOLINT
-#define kForbiddenError "Invalid e-mail or password!"
-#define kUnsupportedAppError "This version of the app is not supported any more. Please visit Toggl website to download a supported app." // NOLINT
-#define kUnauthorizedError "Unauthorized! Please login again."
-#define kCannotConnectError "Cannot connect to Toggl"
-#define kCannotSyncInTestEnv "Cannot sync in test env"
-#define kBackendIsDownError "Backend is down"
-#define kBadRequestError "Data that you are sending is not valid/acceptable"
-#define kRequestIsNotPossible "Request is not possible"
-#define kPaymentRequiredError "Requested action allowed only for Non-Free workspaces. Please upgrade!"  // NOLINT
-#define kCannotAccessWorkspaceError "cannot access workspace"
-#define kEmailNotFoundCannotLogInOffline "Login failed. Are you online?"  // NOLINT
-#define kInvalidPassword "Invalid password"
-#define kCannotEstablishProxyConnection "Cannot establish proxy connection"
-#define kCertificateVerifyFailed "certificate verify failed"
-#define kCheckYourProxySetup "Check your proxy setup"
-#define kCheckYourFirewall "Check your firewall"
-#define kProxyAuthenticationRequired "Proxy Authentication Required"
-#define kCertificateValidationError "Certificate validation error"
-#define kUnacceptableCertificate "Unacceptable certificate from www.toggl.com"
-#define kCannotUpgradeToWebSocketConnection "Cannot upgrade to WebSocket connection"  // NOLINT
-#define kSSLException "SSL Exception"
-#define kRateLimit "Too many requests, sync delayed by 1 minute"
-#define kCannotWriteFile "Cannot write file"
-#define kIsSuspended "is suspended"
-#define kRequestToServerFailedWithStatusCode403 "Request to server failed with status code: 403"  // NOLINT
-#define kMissingWorkspaceID "Missing workspace ID"
-#define kCannotContinueDeletedTimeEntry "Cannot continue deleted time entry"
-#define kCannotDeleteDeletedTimeEntry "Cannot delete deleted time entry"
-#define kErrorRuleAlreadyExists "rule already exists"
-#define kPleaseSelectAWorkspace "Please select a workspace"
-#define kClientNameMustNotBeEmpty "Client name must not be empty"
-#define kProjectNameMustNotBeEmpty "Project name must not be empty"
-#define kProjectNameAlready "Project name already"
-#define kProjectNameAlreadyExists "Project name already exists"
-#define kClientNameAlreadyExists "Client name already exists"
-#define kDatabaseDiskMalformed "The database disk image is malformed"
-#define kMissingWS "You no longer have access to your last workspace"
-#define kOutOfDatePleaseUpgrade "Your version of Toggl Desktop is out of date, please upgrade!"
-#define kThisEntryCantBeSavedPleaseAdd "This entry can't be saved - please add"
-
 #define kModelAutotrackerRule "autotracker_rule"
 #define kModelClient "client"
 #define kModelProject "project"
diff --git a/src/context.cc b/src/context.cc
index 16ad71d180..2b9a5b43b7 100644
--- a/src/context.cc
+++ b/src/context.cc
@@ -38,7 +38,6 @@
 #include <Poco/File.h>
 #include <Poco/FileStream.h>
 #include <Poco/FormattingChannel.h>
-#include <Poco/Logger.h>
 #include <Poco/Net/FilePartSource.h>
 #include <Poco/Net/HTMLForm.h>
 #include <Poco/Net/HTTPStreamFactory.h>
@@ -191,11 +190,11 @@ void Context::stopActivities() {
             }
         }
     } catch(const Poco::Exception& exc) {
-        logger().debug(exc.displayText());
+        logger.debug(exc.displayText());
     } catch(const std::exception& ex) {
-        logger().debug(ex.what());
+        logger.debug(ex.what());
     } catch(const std::string & ex) {
-        logger().debug(ex);
+        logger.debug(ex);
     }
 
     {
@@ -236,7 +235,7 @@ void Context::Shutdown() {
 
 error Context::StartEvents() {
     try {
-        logger().debug("StartEvents");
+        logger.debug("StartEvents");
 
         {
             Poco::Mutex::ScopedLock lock(user_m_);
@@ -252,10 +251,10 @@ error Context::StartEvents() {
         // Check that UI is wired up
         error err = UI()->VerifyCallbacks();
         if (err != noError) {
-            logger().error(err);
+            logger.error(err);
             std::cerr << err << std::endl;
             std::cout << err << std::endl;
-            return displayError("UI is not properly wired up!");
+            return displayError(err);
         }
 
         UIElements render;
@@ -279,7 +278,7 @@ error Context::StartEvents() {
 
         // Set since param to 0 to force full sync on app start
         user->SetSince(0);
-        logger().debug("fullSyncOnAppStart");
+        logger.debug("fullSyncOnAppStart");
 
         updateUI(UIElements::Reset());
 
@@ -310,7 +309,7 @@ error Context::StartEvents() {
 }
 
 error Context::save(const bool push_changes) {
-    logger().debug("save");
+    logger.debug("save");
     try {
         std::vector<ModelChange> changes;
 
@@ -329,7 +328,7 @@ error Context::save(const bool push_changes) {
         updateUI(render);
 
         if (push_changes) {
-            logger().debug("onPushChanges executing");
+            logger.debug("onPushChanges executing");
 
             // Always sync asyncronously with syncerActivity
             trigger_push_ = true;
@@ -338,11 +337,11 @@ error Context::save(const bool push_changes) {
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -496,7 +495,7 @@ void UIElements::ApplyChanges(
 }
 
 void Context::OpenTimeEntryList() {
-    logger().debug("OpenTimeEntryList");
+    logger.debug("OpenTimeEntryList");
 
     UIElements render;
     render.open_time_entry_list = true;
@@ -505,7 +504,7 @@ void Context::OpenTimeEntryList() {
 }
 
 void Context::updateUI(const UIElements &what) {
-    logger().debug("updateUI " + what.String());
+    logger.debug("updateUI " + what.String());
 
     view::TimeEntry editor_time_entry_view;
 
@@ -1017,7 +1016,7 @@ bool Context::isPostponed(
     }
     Poco::Timestamp::TimeDiff diff = value - now;
     if (diff > 2*throttleMicros) {
-        logger().warning(
+        logger.warning(
             "Cannot postpone task, its foo far in the future");
         return false;
     }
@@ -1025,25 +1024,25 @@ bool Context::isPostponed(
 }
 
 error Context::displayError(const error &err) {
-    if ((err.find(kUnauthorizedError) != std::string::npos)) {
+    if (err == error::kUnauthorizedError) {
         if (user_) {
             setUser(nullptr);
         }
     }
-    if (err.find(kUnsupportedAppError) != std::string::npos) {
+    if (err == error::kUnsupportedAppError) {
         urls::SetImATeapot(true);
     } else {
         urls::SetImATeapot(false);
     }
 
-    if (user_ && (err.find(kRequestIsNotPossible) != std::string::npos
-                  || (err.find(kForbiddenError) != std::string::npos))) {
+    if (user_ && (err == error::kRequestIsNotPossible
+                  || (err == error::kForbiddenError))) {
         TogglClient toggl_client(UI());
 
         error err = pullWorkspaces(&toggl_client);
         if (err != noError) {
             // Check for missing WS error and
-            if (err.find(kMissingWS) != std::string::npos) {
+            if (err == error::kMissingWS) {
                 overlay_visible_ = true;
                 UI()->DisplayWSError();
                 return noError;
@@ -1054,28 +1053,22 @@ error Context::displayError(const error &err) {
     return UI()->DisplayError(err);
 }
 
+error Context::displayError(const std::string &err, bool is_user_error) {
+    return UI()->DisplayError(err, is_user_error);
+}
+
 int Context::nextSyncIntervalSeconds() const {
     int n = static_cast<int>(Random::next(kSyncIntervalRangeSeconds)) + kSyncIntervalRangeSeconds;
-    std::stringstream ss;
-    ss << "Next autosync in " << n << " seconds";
-    logger().trace(ss.str());
+    logger.trace("Next autosync in ", n, " seconds");
     return n;
 }
 
 void Context::scheduleSync() {
     Poco::Int64 elapsed_seconds = Poco::Int64(time(nullptr)) - last_sync_started_;
-
-    {
-        std::stringstream ss;
-        ss << "scheduleSync elapsed_seconds=" << elapsed_seconds;
-        logger().debug(ss.str());
-    }
+    logger.debug("scheduleSync elapsed_seconds=", elapsed_seconds);
 
     if (elapsed_seconds < sync_interval_seconds_) {
-        std::stringstream ss;
-        ss << "Last sync attempt less than " << sync_interval_seconds_
-           << " seconds ago, chill";
-        logger().trace(ss.str());
+        logger.trace("Last sync attempt less than ", sync_interval_seconds_, " seconds ago, chill");
         return;
     }
 
@@ -1088,7 +1081,7 @@ void Context::FullSync() {
 }
 
 void Context::Sync() {
-    logger().debug("Sync");
+    logger.debug("Sync");
 
     if (!user_) {
         return;
@@ -1137,9 +1130,7 @@ void Context::onProjectAutocompletes(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::setOnline(const std::string &reason) {
-    std::stringstream ss;
-    ss << "setOnline, reason:" << reason;
-    logger().debug(ss.str());
+    logger.debug("setOnline, reason:", reason);
 
     if (quit_) {
         return;
@@ -1151,7 +1142,7 @@ void Context::setOnline(const std::string &reason) {
 }
 
 void Context::switchWebSocketOff() {
-    logger().debug("switchWebSocketOff");
+    logger.debug("switchWebSocketOff");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>(
@@ -1162,20 +1153,18 @@ void Context::switchWebSocketOff() {
 }
 
 void Context::onSwitchWebSocketOff(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onSwitchWebSocketOff");
+    logger.debug("onSwitchWebSocketOff");
 
     Poco::Mutex::ScopedLock lock(ws_client_m_);
     ws_client_.Shutdown();
 }
 
 error Context::LoadUpdateFromJSONString(const std::string &json) {
-    std::stringstream ss;
-    ss << "LoadUpdateFromJSONString json=" << json;
-    logger().debug(ss.str());
+    logger.debug("LoadUpdateFromJSONString json=", json);
 
     Poco::Mutex::ScopedLock lock(user_m_);
     if (!user_) {
-        logger().warning("User is logged out, cannot update");
+        logger.warning("User is logged out, cannot update");
         return noError;
     }
 
@@ -1197,7 +1186,7 @@ error Context::LoadUpdateFromJSONString(const std::string &json) {
 }
 
 void Context::switchWebSocketOn() {
-    logger().debug("switchWebSocketOn");
+    logger.debug("switchWebSocketOn");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>(
@@ -1208,7 +1197,7 @@ void Context::switchWebSocketOn() {
 }
 
 void Context::onSwitchWebSocketOn(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onSwitchWebSocketOn");
+    logger.debug("onSwitchWebSocketOn");
 
     std::string apitoken("");
 
@@ -1220,7 +1209,7 @@ void Context::onSwitchWebSocketOn(Poco::Util::TimerTask&) {  // NOLINT
     }
 
     if (apitoken.empty()) {
-        logger().error("No API token, cannot switch Websocket on");
+        logger.error("No API token, cannot switch Websocket on");
         return;
     }
 
@@ -1232,7 +1221,7 @@ void Context::onSwitchWebSocketOn(Poco::Util::TimerTask&) {  // NOLINT
 
 // Start/stop timeline recording on local machine
 void Context::switchTimelineOff() {
-    logger().debug("switchTimelineOff");
+    logger.debug("switchTimelineOff");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>(
@@ -1243,7 +1232,7 @@ void Context::switchTimelineOff() {
 }
 
 void Context::onSwitchTimelineOff(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onSwitchTimelineOff");
+    logger.debug("onSwitchTimelineOff");
 
     {
         Poco::Mutex::ScopedLock lock(timeline_uploader_m_);
@@ -1255,7 +1244,7 @@ void Context::onSwitchTimelineOff(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::switchTimelineOn() {
-    logger().debug("switchTimelineOn");
+    logger.debug("switchTimelineOn");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>(
@@ -1270,7 +1259,7 @@ void Context::switchTimelineOn() {
 }
 
 void Context::onSwitchTimelineOn(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onSwitchTimelineOn");
+    logger.debug("onSwitchTimelineOn");
 
     if (quit_) {
         return;
@@ -1294,7 +1283,7 @@ void Context::onSwitchTimelineOn(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::fetchUpdates() {
-    logger().debug("fetchUpdates");
+    logger.debug("fetchUpdates");
 
     next_fetch_updates_at_ =
         postpone(kRequestThrottleSeconds * kOneSecondInMicros);
@@ -1305,16 +1294,13 @@ void Context::fetchUpdates() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_fetch_updates_at_);
 
-    std::stringstream ss;
-    ss << "Next update fetch at "
-       << Formatter::Format8601(next_fetch_updates_at_);
-    logger().debug(ss.str());
+    logger.debug("Next update fetch at ", Formatter::Format8601(next_fetch_updates_at_));
 }
 
 void Context::onFetchUpdates(Poco::Util::TimerTask&) {  // NOLINT
     if (isPostponed(next_fetch_updates_at_,
                     kRequestThrottleSeconds * kOneSecondInMicros)) {
-        logger().debug("onFetchUpdates postponed");
+        logger.debug("onFetchUpdates postponed");
         return;
     }
 
@@ -1322,7 +1308,7 @@ void Context::onFetchUpdates(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::startPeriodicSync() {
-    logger().trace("startPeriodicSync");
+    logger.trace("startPeriodicSync");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>
@@ -1335,14 +1321,11 @@ void Context::startPeriodicSync() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_periodic_sync_at_);
 
-    std::stringstream ss;
-    ss << "Next periodic sync at "
-       << Formatter::Format8601(next_periodic_sync_at_);
-    logger().debug(ss.str());
+    logger.debug("Next periodic sync at ", Formatter::Format8601(next_periodic_sync_at_));
 }
 
 void Context::onPeriodicSync(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onPeriodicSync");
+    logger.debug("onPeriodicSync");
 
     scheduleSync();
 
@@ -1350,7 +1333,7 @@ void Context::onPeriodicSync(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::startPeriodicUpdateCheck() {
-    logger().debug("startPeriodicUpdateCheck");
+    logger.debug("startPeriodicUpdateCheck");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>
@@ -1362,14 +1345,11 @@ void Context::startPeriodicUpdateCheck() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_periodic_check_at);
 
-    std::stringstream ss;
-    ss << "Next periodic update check at "
-       << Formatter::Format8601(next_periodic_check_at);
-    logger().debug(ss.str());
+    logger.debug("Next periodic update check at ", Formatter::Format8601(next_periodic_check_at));
 }
 
 void Context::onPeriodicUpdateCheck(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onPeriodicUpdateCheck");
+    logger.debug("onPeriodicUpdateCheck");
 
     executeUpdateCheck();
 
@@ -1377,7 +1357,7 @@ void Context::onPeriodicUpdateCheck(Poco::Util::TimerTask&) {  // NOLINT
 }
 
 void Context::startPeriodicInAppMessageCheck() {
-    logger().debug("startPeriodicInAppMessageCheck");
+    logger.debug("startPeriodicInAppMessageCheck");
 
     Poco::Util::TimerTask::Ptr ptask =
         new Poco::Util::TimerTaskAdapter<Context>
@@ -1389,14 +1369,11 @@ void Context::startPeriodicInAppMessageCheck() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_periodic_check_at);
 
-    std::stringstream ss;
-    ss << "Next periodic in-app message check at "
-       << Formatter::Format8601(next_periodic_check_at);
-    logger().debug(ss.str());
+    logger.debug("Next periodic in-app message check at ", Formatter::Format8601(next_periodic_check_at));
 }
 
 void Context::onPeriodicInAppMessageCheck(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onPeriodicInAppMessageChec");
+    logger.debug("onPeriodicInAppMessageChec");
 
     fetchMessage(1);
 }
@@ -1407,7 +1384,7 @@ error Context::UpdateChannel(
 
     error err = db()->LoadUpdateChannel(update_channel);
 
-    if (err.find(kDatabaseDiskMalformed) != std::string::npos) {
+    if (err == error::kDatabaseDiskMalformed) {
         err = noError;
     }
     return displayError(err);
@@ -1430,7 +1407,7 @@ std::string Context::UserEmail() {
 }
 
 void Context::executeUpdateCheck() {
-    logger().debug("executeUpdateCheck");
+    logger.debug("executeUpdateCheck");
 
     displayError(downloadUpdate());
 }
@@ -1443,7 +1420,7 @@ error Context::downloadUpdate() {
 
         // To test updater in development, comment this block out:
         if ("production" != environment_) {
-            logger().debug("Not in production, will not download updates");
+            logger.debug("Not in production, will not download updates");
             return noError;
         }
 
@@ -1455,7 +1432,7 @@ error Context::downloadUpdate() {
         }
 
         if (HTTPSClient::Config.AppVersion.empty()) {
-            return error("This version cannot check for updates. This has been probably already fixed. Please check https://toggl.com/toggl-desktop/ for a newer version.");
+            return error::kCannotCheckForUpdates;
         }
 
         // Ask Toggl server if we have updates
@@ -1483,23 +1460,21 @@ error Context::downloadUpdate() {
             Json::Value root;
             Json::Reader reader;
             if (!reader.parse(resp.body, root)) {
-                return error("Error parsing update check response body");
+                return error::kFailedToParseData;
             }
             auto latestVersion = root[shortOSName()][update_channel];
             url = latestVersion[installerPlatform()].asString();
             auto versionNumberJsonToken = latestVersion["version"];
             if (versionNumberJsonToken.empty()) {
-                return error("No versions found for OS " + shortOSName() + ", platform " + installerPlatform() + ", channel " + update_channel);
+                logger.warning("No versions found for OS " + shortOSName() + ", platform " + installerPlatform() + ", channel " + update_channel);
+                return error::kCannotCheckForUpdates;
             }
             version_number = versionNumberJsonToken.asString();
 
             if (lessThanVersion(HTTPSClient::Config.AppVersion, version_number)) {
-                std::stringstream ss;
-                ss << "Found update " << version_number
-                   << " (" << url << ")";
-                logger().debug(ss.str());
+                logger.debug("Found update ", version_number, " (", url, ")");
             } else {
-                logger().debug("The app is up to date");
+                logger.debug("The app is up to date");
                 if (UI()->CanDisplayUpdate()) {
                     UI()->DisplayUpdate("");
                 }
@@ -1516,13 +1491,14 @@ error Context::downloadUpdate() {
 
         // we need a path to download to, when going this way
         if (update_path_.empty()) {
-            return error("update path is empty, cannot download update");
+            logger.log("update path is empty, cannot download update");
+            return error::kCannotCheckForUpdates;
         }
 
         // Ignore update if not compatible with this client version
         // only windows .exe installers are supported atm
         if (url.find(".exe") == std::string::npos) {
-            logger().debug("Update is not compatible with this client,"
+            logger.debug("Update is not compatible with this client,"
                            " will ignore");
             return noError;
         }
@@ -1540,7 +1516,7 @@ error Context::downloadUpdate() {
 
             Poco::File f(file);
             if (f.exists()) {
-                logger().debug("File already exists: " + file);
+                logger.debug("File already exists: " + file);
                 return noError;
             }
 
@@ -1566,11 +1542,11 @@ error Context::downloadUpdate() {
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -1580,13 +1556,13 @@ error Context::fetchMessage(const bool periodic) {
 
         // Check if in-app messaging is supported and show
         if (!UI()->CanDisplayMessage()) {
-            logger().debug("In-app messages not supported on this platform");
+            logger.debug("In-app messages not supported on this platform");
             return noError;
         }
 
         // To test in-app message fetch in development, comment this block out:
         if ("production" != environment_) {
-            logger().debug("Not in production, will not fetch in-app messages");
+            logger.debug("Not in production, will not fetch in-app messages");
             return noError;
         }
 
@@ -1598,7 +1574,7 @@ error Context::fetchMessage(const bool periodic) {
         }
 
         if (HTTPSClient::Config.AppVersion.empty()) {
-            return error("AppVersion missing!");
+            return error::kCannotCheckForUpdates;
         }
 
         // Fetch latest message
@@ -1627,7 +1603,7 @@ error Context::fetchMessage(const bool periodic) {
             Json::Value root;
             Json::Reader reader;
             if (!reader.parse(resp.body, root)) {
-                return error("Error parsing in-app message response body");
+                return error::kFailedToParseData;
             }
 
             // check all required fields
@@ -1640,7 +1616,7 @@ error Context::fetchMessage(const bool periodic) {
                     !root.isMember("url-mac") ||
                     !root.isMember("url-win") ||
                     !root.isMember("url-linux")) {
-                logger().debug("Required fields are missing in in-app message JSON");
+                logger.debug("Required fields are missing in in-app message JSON");
                 return noError;
             }
 
@@ -1721,11 +1697,11 @@ error Context::fetchMessage(const bool periodic) {
             button,
             url);
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -1796,7 +1772,7 @@ bool Context::lessThanVersion(const std::string& version1, const std::string& ve
 }
 
 void Context::TimelineUpdateServerSettings() {
-    logger().debug("TimelineUpdateServerSettings");
+    logger.debug("TimelineUpdateServerSettings");
 
     next_update_timeline_settings_at_ =
         postpone(kRequestThrottleSeconds * kOneSecondInMicros);
@@ -1807,10 +1783,7 @@ void Context::TimelineUpdateServerSettings() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_update_timeline_settings_at_);
 
-    std::stringstream ss;
-    ss << "Next timeline settings update at "
-       << Formatter::Format8601(next_update_timeline_settings_at_);
-    logger().debug(ss.str());
+    logger.debug("Next timeline settings update at ", Formatter::Format8601(next_update_timeline_settings_at_));
 }
 
 const std::string kRecordTimelineEnabledJSON = "{\"record_timeline\": true}";
@@ -1819,11 +1792,11 @@ const std::string kRecordTimelineDisabledJSON = "{\"record_timeline\": false}";
 void Context::onTimelineUpdateServerSettings(Poco::Util::TimerTask&) {  // NOLINT
     if (isPostponed(next_update_timeline_settings_at_,
                     kRequestThrottleSeconds * kOneSecondInMicros)) {
-        logger().debug("onTimelineUpdateServerSettings postponed");
+        logger.debug("onTimelineUpdateServerSettings postponed");
         return;
     }
 
-    logger().debug("onTimelineUpdateServerSettings executing");
+    logger.debug("onTimelineUpdateServerSettings executing");
 
     std::string apitoken("");
     std::string json(kRecordTimelineDisabledJSON);
@@ -1851,14 +1824,14 @@ void Context::onTimelineUpdateServerSettings(Poco::Util::TimerTask&) {  // NOLIN
     HTTPSResponse resp = client.Post(req);
     if (resp.err != noError) {
         displayError(resp.err);
-        logger().error(resp.body);
-        logger().error(resp.err);
+        logger.error(resp.body);
+        logger.error(resp.err);
     }
 }
 
 error Context::SendFeedback(const Feedback &fb) {
     if (!user_) {
-        logger().warning("Cannot send feedback, user logged out");
+        logger.warning("Cannot send feedback, user logged out");
         return noError;
     }
 
@@ -1882,7 +1855,7 @@ error Context::SendFeedback(const Feedback &fb) {
 }
 
 void Context::onSendFeedback(Poco::Util::TimerTask&) {  // NOLINT
-    logger().debug("onSendFeedback");
+    logger.debug("onSendFeedback");
 
     std::string api_token_value("");
     std::string api_token_name("");
@@ -1955,7 +1928,7 @@ void Context::onSendFeedback(Poco::Util::TimerTask&) {  // NOLINT
 
     TogglClient client(UI());
     HTTPSResponse resp = client.Post(req);
-    logger().debug("Feedback result: " + resp.err);
+    logger.debug("Feedback result: " + resp.err.String());
     if (resp.err != noError) {
         displayError(resp.err);
         return;
@@ -2327,7 +2300,7 @@ error Context::SetProxySettings(
 }
 
 void Context::OpenSettings() {
-    logger().debug("OpenSettings");
+    logger.debug("OpenSettings");
 
     UIElements render;
     render.display_settings = true;
@@ -2338,13 +2311,11 @@ void Context::OpenSettings() {
 error Context::SetDBPath(
     const std::string &path) {
     try {
-        std::stringstream ss;
-        ss << "SetDBPath " << path;
-        logger().debug(ss.str());
+        logger.debug("SetDBPath ", path);
 
         Poco::Mutex::ScopedLock lock(db_m_);
         if (db_) {
-            logger().debug("delete db_ from SetDBPath()");
+            logger.debug("delete db_ from SetDBPath()");
             delete db_;
             db_ = nullptr;
         }
@@ -2363,12 +2334,10 @@ void Context::SetEnvironment(const std::string &value) {
     if (!("production" == value ||
             "development" == value ||
             "test" == value)) {
-        std::stringstream ss;
-        ss << "Invalid environment '" << value << "'!";
-        logger().error(ss.str());
+        logger.error("Invalid environment '", value, "'!");
         return;
     }
-    logger().debug("SetEnvironment " + value);
+    logger.debug("SetEnvironment " + value);
     environment_ = value;
 
     HTTPSClient::Config.IgnoreCert = ("development" == environment_);
@@ -2391,11 +2360,11 @@ error Context::AsyncGoogleLogin(const std::string &access_token) {
 error Context::attemptOfflineLogin(const std::string &email,
                                    const std::string &password) {
     if (email.empty()) {
-        return error("cannot login offline without an e-mail");
+        return error::kOfflineLoginMissingEmail;
     }
 
     if (password.empty()) {
-        return error("cannot login offline without a password");
+        return error::kOfflineLoginMissingPassword;
     }
 
     User *user = new User();
@@ -2408,22 +2377,18 @@ error Context::attemptOfflineLogin(const std::string &email,
 
     if (!user->ID()) {
         delete user;
-        logger().debug("User data not found in local database for " + email);
-        return error(kEmailNotFoundCannotLogInOffline);
+        logger.debug("User data not found in local database for " + email);
+        return error::kEmailNotFoundCannotLogInOffline;
     }
 
     if (user->OfflineData().empty()) {
         delete user;
-        logger().debug("Offline data not found in local database for "
+        logger.debug("Offline data not found in local database for "
                        + email);
-        return error(kEmailNotFoundCannotLogInOffline);
+        return error::kEmailNotFoundCannotLogInOffline;
     }
 
     err = user->SetAPITokenFromOfflineData(password);
-    if ("I/O error" == err || err.find("bad decrypt") != std::string::npos) {
-        delete user;
-        return error(kInvalidPassword);
-    }
     if (err != noError) {
         delete user;
         return err;
@@ -2459,16 +2424,13 @@ error Context::Login(
         std::string json("");
         error err = me(&client, email, password, &json, 0);
         if (err != noError) {
-            if (!IsNetworkingError(err)) {
+            if (err.IsNetworkingError()) {
                 return displayError(err);
             }
             // Indicate we're offline
             displayError(err);
 
-            std::stringstream ss;
-            ss << "Got networking error " << err
-               << " will attempt offline login";
-            logger().debug(ss.str());
+            logger.debug("Got networking error ", err, " will attempt offline login");
 
             return displayError(attemptOfflineLogin(email, password));
         }
@@ -2491,7 +2453,7 @@ error Context::Login(
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().error("cannot enable offline login, no user");
+                logger.error("cannot enable offline login, no user");
                 return noError;
             }
 
@@ -2559,11 +2521,7 @@ error Context::AsyncGoogleSignup(const std::string &access_token,
 }
 
 void Context::setUser(User *value, const bool logged_in) {
-    {
-        std::stringstream ss;
-        ss << "setUser user_logged_in=" << logged_in;
-        logger().debug(ss.str());
-    }
+    logger.debug("setUser user_logged_in=", logged_in);
 
     Poco::UInt64 user_id(0);
 
@@ -2694,13 +2652,13 @@ error Context::SetLoggedInUserFromJSON(
     // Fetch OBM experiments..
     err = pullObmExperiments();
     if (err != noError) {
-        logger().error("Error pulling OBM experiments: " + err);
+        logger.error("Error pulling OBM experiments: ",  err);
     }
 
     // ..and run the OBM experiments
     err = runObmExperiments();
     if (err != noError) {
-        logger().error("Error running OBM experiments: " + err);
+        logger.error("Error running OBM experiments: ",  err);
     }
 
     return noError;
@@ -2709,7 +2667,7 @@ error Context::SetLoggedInUserFromJSON(
 error Context::Logout() {
     try {
         if (!user_) {
-            logger().warning("User is logged out, cannot logout again");
+            logger.warning("User is logged out, cannot logout again");
             return noError;
         }
 
@@ -2718,7 +2676,7 @@ error Context::Logout() {
             return displayError(err);
         }
 
-        logger().debug("setUser from Logout");
+        logger.debug("setUser from Logout");
         overlay_visible_ = false;
         setUser(nullptr);
 
@@ -2749,7 +2707,7 @@ error Context::ClearCache() {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("User is logged out, cannot clear cache");
+                logger.warning("User is logged out, cannot clear cache");
                 return noError;
             }
             err = db()->DeleteUser(user_, true);
@@ -2784,7 +2742,7 @@ TimeEntry *Context::Start(
     // else they will linger around in the app
     // and the user can continue using the unsupported app.
     if (urls::ImATeapot()) {
-        displayError(kUnsupportedAppError);
+        displayError(error::kUnsupportedAppError);
         return nullptr;
     }
 
@@ -2798,7 +2756,7 @@ TimeEntry *Context::Start(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot start tracking, user logged out");
+            logger.warning("Cannot start tracking, user logged out");
             return nullptr;
         }
 
@@ -2857,7 +2815,7 @@ void Context::OpenTimeEntryEditor(
     const bool edit_running_entry,
     const std::string &focused_field_name) {
     if (!edit_running_entry && GUID.empty()) {
-        logger().error("Cannot edit time entry without a GUID");
+        logger.error("Cannot edit time entry without a GUID");
         return;
     }
 
@@ -2866,7 +2824,7 @@ void Context::OpenTimeEntryEditor(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot edit time entry, user logged out");
+            logger.warning("Cannot edit time entry, user logged out");
             return;
         }
 
@@ -2878,7 +2836,7 @@ void Context::OpenTimeEntryEditor(
     }
 
     if (!te) {
-        logger().warning("Time entry not found for edit " + GUID);
+        logger.warning("Time entry not found for edit " + GUID);
         return;
     }
 
@@ -2908,7 +2866,7 @@ TimeEntry *Context::ContinueLatest(const bool prevent_on_app) {
     // else they will linger around in the app
     // and the user can continue using the unsupported app.
     if (urls::ImATeapot()) {
-        displayError(kUnsupportedAppError);
+        displayError(error::kUnsupportedAppError);
         return nullptr;
     }
 
@@ -2922,7 +2880,7 @@ TimeEntry *Context::ContinueLatest(const bool prevent_on_app) {
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot continue tracking, user logged out");
+            logger.warning("Cannot continue tracking, user logged out");
             return nullptr;
         }
 
@@ -2977,7 +2935,7 @@ TimeEntry *Context::Continue(
     // else they will linger around in the app
     // and the user can continue using the unsupported app.
     if (urls::ImATeapot()) {
-        displayError(kUnsupportedAppError);
+        displayError(error::kUnsupportedAppError);
         return nullptr;
     }
 
@@ -2996,7 +2954,7 @@ TimeEntry *Context::Continue(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot continue time entry, user logged out");
+            logger.warning("Cannot continue time entry, user logged out");
             return nullptr;
         }
 
@@ -3029,7 +2987,7 @@ error Context::DeleteTimeEntryByGUID(const std::string &GUID) {
     // else they will linger around in the app
     // and the user can continue using the unsupported app.
     if (urls::ImATeapot()) {
-        return displayError(kUnsupportedAppError);
+        return displayError(error::kUnsupportedAppError);
     }
 
     if (GUID.empty()) {
@@ -3041,18 +2999,18 @@ error Context::DeleteTimeEntryByGUID(const std::string &GUID) {
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot delete time entry, user logged out");
+            logger.warning("Cannot delete time entry, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
         if (te->DeletedAt()) {
-            return displayError(kCannotDeleteDeletedTimeEntry);
+            return displayError(error::kCannotDeleteDeletedTimeEntry);
         }
 
         if (isTimeEntryLocked(te)) {
@@ -3080,12 +3038,12 @@ error Context::SetTimeEntryDuration(
 
     Poco::Mutex::ScopedLock lock(user_m_);
     if (!user_) {
-        logger().warning("Cannot set duration, user logged out");
+        logger.warning("Cannot set duration, user logged out");
         return noError;
     }
     TimeEntry *te = user_->related.TimeEntryByGUID(GUID);
     if (!te) {
-        logger().warning("Time entry not found: " + GUID);
+        logger.warning("Time entry not found: " + GUID);
         return noError;
     }
 
@@ -3096,7 +3054,7 @@ error Context::SetTimeEntryDuration(
     // validate the value
     int seconds = Formatter::ParseDurationString(duration);
     if (seconds >= kMaxDurationSeconds) {
-        return displayError(error(kOverMaxDurationError));
+        return displayError(error::kOverMaxDurationError);
     }
 
     te->SetDurationUserInput(duration);
@@ -3115,13 +3073,13 @@ error Context::SetTimeEntryProject(
 
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot set project, user logged out");
+            logger.warning("Cannot set project, user logged out");
             return noError;
         }
 
         TimeEntry *te = user_->related.TimeEntryByGUID(GUID);
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3138,8 +3096,7 @@ error Context::SetTimeEntryProject(
         }
 
         if (p && !canChangeProjectTo(te, p)) {
-            return displayError(error(
-                "Cannot change project: would end up with locked time entry"));
+            return displayError(error::kTimeEntryWouldBeLockedAfterProjectChange);
         }
 
         if (p) {
@@ -3184,18 +3141,18 @@ error Context::SetTimeEntryDate(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot change date, user logged out");
+            logger.warning("Cannot change date, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
         if (isTimeEntryLocked(te)) {
-            return displayError(error("Cannot change locked time entry."));
+            return displayError(error::kCannotChangeLockedTE);
         }
 
         Poco::LocalDateTime date_part(
@@ -3206,7 +3163,7 @@ error Context::SetTimeEntryDate(
 
         // Validate date input
         if (date_part.year() < kMinimumAllowedYear || date_part.year() > kMaximumAllowedYear) {
-            return displayError(error(kInvalidDateError));
+            return displayError(error::kInvalidDateError);
         }
 
         dt = Poco::LocalDateTime(
@@ -3214,9 +3171,7 @@ error Context::SetTimeEntryDate(
             time_part.hour(), time_part.minute(), time_part.second());
 
         if (!canChangeStartTimeTo(te, dt.timestamp().epochTime())) {
-            return displayError(
-                error(
-                    "Failed to change time entry date: workspace is locked."));
+            return displayError("Failed to change time entry date: workspace is locked.", true);
         }
     }
 
@@ -3236,13 +3191,13 @@ error Context::SetTimeEntryStart(const std::string GUID,
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot change start time, user logged out");
+            logger.warning("Cannot change start time, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3270,13 +3225,13 @@ error Context::SetTimeEntryStart(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot change start time, user logged out");
+            logger.warning("Cannot change start time, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3289,12 +3244,12 @@ error Context::SetTimeEntryStart(
 
     // Validate time input
     if (local.year() < kMinimumAllowedYear || local.year() > kMaximumAllowedYear) {
-        return displayError(error(kInvalidStartTimeError));
+        return displayError(error::kInvalidStartTimeError);
     }
 
     int hours(0), minutes(0);
     if (!toggl::Formatter::ParseTimeInput(value, &hours, &minutes)) {
-        return error("invalid time format");
+        return error::kInvalidTimeFormat;
     }
 
     Poco::LocalDateTime dt(
@@ -3323,13 +3278,13 @@ error Context::SetTimeEntryStop(const std::string GUID,
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot change stop time, user logged out");
+            logger.warning("Cannot change stop time, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3356,13 +3311,13 @@ error Context::SetTimeEntryStop(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot change stop time, user logged out");
+            logger.warning("Cannot change stop time, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3376,7 +3331,7 @@ error Context::SetTimeEntryStop(
 
     int hours(0), minutes(0);
     if (!toggl::Formatter::ParseTimeInput(value, &hours, &minutes)) {
-        return error("invalid time format");
+        return error::kInvalidTimeFormat;
     }
 
 // By default, keep end date, only change hour && minute
@@ -3419,13 +3374,13 @@ error Context::SetTimeEntryTags(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot set tags, user logged out");
+            logger.warning("Cannot set tags, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3456,13 +3411,13 @@ error Context::SetTimeEntryBillable(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot set billable, user logged out");
+            logger.warning("Cannot set billable, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3493,13 +3448,13 @@ error Context::SetTimeEntryDescription(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot set description, user logged out");
+            logger.warning("Cannot set description, user logged out");
             return noError;
         }
         te = user_->related.TimeEntryByGUID(GUID);
 
         if (!te) {
-            logger().warning("Time entry not found: " + GUID);
+            logger.warning("Time entry not found: " + GUID);
             return noError;
         }
 
@@ -3510,7 +3465,7 @@ error Context::SetTimeEntryDescription(
 
     // Validate description length
     if (value.length() > kMaximumDescriptionLength) {
-        return displayError(error(kMaximumDescriptionLengthError));
+        return displayError(error::kMaximumDescriptionLengthError);
     }
 
     te->SetDescription(value);
@@ -3529,7 +3484,7 @@ error Context::Stop(const bool prevent_on_app) {
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot stop tracking, user logged out");
+            logger.warning("Cannot stop tracking, user logged out");
             return noError;
         }
         user_->Stop(&stopped);
@@ -3538,7 +3493,7 @@ error Context::Stop(const bool prevent_on_app) {
     }
 
     if (stopped.empty()) {
-        logger().warning("No time entry was found to stop");
+        logger.warning("No time entry was found to stop");
         return noError;
     }
 
@@ -3566,15 +3521,15 @@ error Context::DiscardTimeAt(
 
     // Tracking action
     if ("production" == environment_) {
-        std::stringstream ss;
+        std::string method;
         if (split_into_new_entry) {
-            ss << "idle-as-new-entry";
+            method = "idle-as-new-entry";
         } else {
-            ss << "discard-and-stop";
+            method = "discard-and-stop";
         }
 
         analytics_.TrackIdleDetectionClick(db_->AnalyticsClientID(),
-                                           ss.str());
+                                           method);
     }
 
     TimeEntry *split = nullptr;
@@ -3582,7 +3537,7 @@ error Context::DiscardTimeAt(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot stop time entry, user logged out");
+            logger.warning("Cannot stop time entry, user logged out");
             return noError;
         }
 
@@ -3622,7 +3577,7 @@ TimeEntry *Context::DiscardTimeAndContinue(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot stop time entry, user logged out");
+            logger.warning("Cannot stop time entry, user logged out");
             return nullptr;
         }
         user_->DiscardTimeAt(guid, at, false);
@@ -3640,7 +3595,7 @@ TimeEntry *Context::DiscardTimeAndContinue(
 TimeEntry *Context::RunningTimeEntry() {
     Poco::Mutex::ScopedLock lock(user_m_);
     if (!user_) {
-        logger().warning("Cannot fetch time entry, user logged out");
+        logger.warning("Cannot fetch time entry, user logged out");
         return nullptr;
     }
     return user_->RunningTimeEntry();
@@ -3649,7 +3604,7 @@ TimeEntry *Context::RunningTimeEntry() {
 error Context::ToggleTimelineRecording(const bool record_timeline) {
     Poco::Mutex::ScopedLock lock(user_m_);
     if (!user_) {
-        logger().warning("Cannot toggle timeline, user logged out");
+        logger.warning("Cannot toggle timeline, user logged out");
         return noError;
     }
     try {
@@ -3702,7 +3657,7 @@ error Context::SetDefaultProject(
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot set default PID, user logged out");
+                logger.warning("Cannot set default PID, user logged out");
                 return noError;
             }
 
@@ -3759,7 +3714,7 @@ error Context::DefaultProjectName(std::string *name) {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot get default PID, user logged out");
+                logger.warning("Cannot get default PID, user logged out");
                 return noError;
             }
             if (user_->DefaultPID()) {
@@ -3787,7 +3742,7 @@ error Context::DefaultPID(Poco::UInt64 *result) {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot get default PID, user logged out");
+                logger.warning("Cannot get default PID, user logged out");
                 return noError;
             }
             *result = user_->DefaultPID();
@@ -3809,7 +3764,7 @@ error Context::DefaultTID(Poco::UInt64 *result) {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot get default PID, user logged out");
+                logger.warning("Cannot get default PID, user logged out");
                 return noError;
             }
             *result = user_->DefaultTID();
@@ -3847,12 +3802,12 @@ error Context::AddAutotrackerRule(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("cannot add autotracker rule, user logged out");
+            logger.warning("cannot add autotracker rule, user logged out");
             return noError;
         }
         if (user_->related.HasMatchingAutotrackerRule(lowercase)) {
             // avoid duplicates
-            return displayError(kErrorRuleAlreadyExists);
+            return displayError(error::kErrorRuleAlreadyExists);
         }
 
         Task *t = nullptr;
@@ -3912,7 +3867,7 @@ error Context::DeleteAutotrackerRule(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("cannot delete rule, user is logged out");
+            logger.warning("cannot delete rule, user is logged out");
             return noError;
         }
 
@@ -3934,7 +3889,7 @@ Project *Context::CreateProject(
     const std::string &project_color) {
 
     if (!workspace_id) {
-        displayError(kPleaseSelectAWorkspace);
+        displayError(error::kPleaseSelectAWorkspace);
         return nullptr;
     }
 
@@ -3945,7 +3900,7 @@ Project *Context::CreateProject(
         return nullptr;
     }
     if (trimmed_project_name.empty()) {
-        displayError(kProjectNameMustNotBeEmpty);
+        displayError(error::kProjectNameMustNotBeEmpty);
         return nullptr;
     }
 
@@ -3954,7 +3909,7 @@ Project *Context::CreateProject(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot add project, user logged out");
+            logger.warning("Cannot add project, user logged out");
             return nullptr;
         }
         for (std::vector<Project *>::iterator it =
@@ -3972,7 +3927,7 @@ Project *Context::CreateProject(
             }
 
             if (clientIsSame && p->Name() == trimmed_project_name) {
-                displayError(kProjectNameAlreadyExists);
+                displayError(error::kProjectNameAlreadyExists);
                 return nullptr;
             }
         }
@@ -4028,7 +3983,8 @@ error Context::AddObmAction(
     const std::string &value) {
     // Check input
     if (!experiment_id) {
-        return error("missing experiment_id");
+        logger.log(__FUNCTION__, "missing experiment_id");
+        return error::kCannotCreateObmAction;
     }
     std::string trimmed_key("");
     error err = db_->Trim(key, &trimmed_key);
@@ -4036,7 +3992,8 @@ error Context::AddObmAction(
         return displayError(err);
     }
     if (trimmed_key.empty()) {
-        return error("missing key");
+        logger.log(__FUNCTION__, "missing trimmed_key");
+        return error::kCannotCreateObmAction;
     }
     std::string trimmed_value("");
     err = db_->Trim(value, &trimmed_value);
@@ -4044,13 +4001,14 @@ error Context::AddObmAction(
         return displayError(err);
     }
     if (trimmed_value.empty()) {
-        return error("missing value");
+        logger.log(__FUNCTION__, "missing trimmed_value");
+        return error::kCannotCreateObmAction;
     }
     // Add OBM action and save
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot create a OBM action, user logged out");
+            logger.warning("Cannot create a OBM action, user logged out");
             return noError;
         }
         ObmAction *action = new ObmAction();
@@ -4068,7 +4026,7 @@ Client *Context::CreateClient(
     const std::string &client_name) {
 
     if (!workspace_id) {
-        displayError(kPleaseSelectAWorkspace);
+        displayError(error::kPleaseSelectAWorkspace);
         return nullptr;
     }
 
@@ -4079,7 +4037,7 @@ Client *Context::CreateClient(
         return nullptr;
     }
     if (trimmed_client_name.empty()) {
-        displayError(kClientNameMustNotBeEmpty);
+        displayError(error::kClientNameMustNotBeEmpty);
         return nullptr;
     }
 
@@ -4088,7 +4046,7 @@ Client *Context::CreateClient(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("Cannot create a client, user logged out");
+            logger.warning("Cannot create a client, user logged out");
             return nullptr;
         }
         for (std::vector<Client *>::iterator it =
@@ -4096,7 +4054,7 @@ Client *Context::CreateClient(
                 it != user_->related.Clients.end(); ++it) {
             Client *c = *it;
             if (c->WID() == workspace_id && c->Name() == trimmed_client_name) {
-                displayError(kClientNameAlreadyExists);
+                displayError(error::kClientNameAlreadyExists);
                 return nullptr;
             }
         }
@@ -4119,7 +4077,7 @@ void Context::SetSleep() {
 
     // Set Sleep as usual
     if (!isHandled) {
-        logger().debug("SetSleep");
+        logger.debug("SetSleep");
         idle_.SetSleep();
         if (window_change_recorder_) {
             window_change_recorder_->SetIsSleeping(true);
@@ -4140,7 +4098,7 @@ error Context::OpenReportsInBrowser() {
     // else they will linger around in the app
     // and the user can continue using the unsupported app.
     if (urls::ImATeapot()) {
-        return displayError(kUnsupportedAppError);
+        return displayError(error::kUnsupportedAppError);
     }
 
     std::string apitoken("");
@@ -4250,7 +4208,7 @@ error Context::runObmExperiments() {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("User logged out, cannot OBM experiment");
+                logger.warning("User logged out, cannot OBM experiment");
                 return noError;
             }
             for (std::vector<ObmExperiment *>::const_iterator it =
@@ -4291,7 +4249,7 @@ error Context::runObmExperiments() {
 }
 
 void Context::SetWake() {
-    logger().debug("SetWake");
+    logger.debug("SetWake");
 
     Poco::Timestamp::TimeDiff delay = 0;
     if (next_wake_at_ > 0) {
@@ -4305,19 +4263,16 @@ void Context::SetWake() {
     Poco::Mutex::ScopedLock lock(timer_m_);
     timer_.schedule(ptask, next_wake_at_);
 
-    std::stringstream ss;
-    ss << "Next wake at "
-       << Formatter::Format8601(next_wake_at_);
-    logger().debug(ss.str());
+    logger.debug("Next wake at ", Formatter::Format8601(next_wake_at_));
 }
 
 void Context::onWake(Poco::Util::TimerTask&) {  // NOLINT
     if (isPostponed(next_wake_at_,
                     kRequestThrottleSeconds * kOneSecondInMicros)) {
-        logger().debug("onWake postponed");
+        logger.debug("onWake postponed");
         return;
     }
-    logger().debug("onWake executing");
+    logger.debug("onWake executing");
 
     try {
         Poco::LocalDateTime now;
@@ -4337,32 +4292,32 @@ void Context::onWake(Poco::Util::TimerTask&) {  // NOLINT
         Sync();
     }
     catch (const Poco::Exception& exc) {
-        logger().error(exc.displayText());
+        logger.error(exc.displayText());
     }
     catch (const std::exception& ex) {
-        logger().error(ex.what());
+        logger.error(ex.what());
     }
     catch (const std::string & ex) {
-        logger().error(ex);
+        logger.error(ex);
     }
 }
 
 void Context::SetLocked() {
-    logger().debug("SetLocked");
+    logger.debug("SetLocked");
     if (window_change_recorder_) {
         window_change_recorder_->SetIsLocked(true);
     }
 }
 
 void Context::SetUnlocked() {
-    logger().debug("SetUnlocked");
+    logger.debug("SetUnlocked");
     if (window_change_recorder_) {
         window_change_recorder_->SetIsLocked(false);
     }
 }
 
 void Context::SetOnline() {
-    logger().debug("SetOnline");
+    logger.debug("SetOnline");
     Sync();
 }
 
@@ -4413,7 +4368,7 @@ void Context::displayReminder() {
         (Poco::DateTime::FRIDAY == wday && !settings_.remind_fri) ||
         (Poco::DateTime::SATURDAY == wday && !settings_.remind_sat) ||
         (Poco::DateTime::SUNDAY == wday && !settings_.remind_sun)) {
-        logger().debug("reminder is not enabled on this weekday");
+        logger.debug("reminder is not enabled on this weekday");
         return;
     }
 
@@ -4424,11 +4379,7 @@ void Context::displayReminder() {
             Poco::LocalDateTime start(
                 now.year(), now.month(), now.day(), h, m, now.second());
             if (now < start) {
-                std::stringstream ss;
-                ss << "Reminder - its too early for reminders"
-                   << " [" << now.hour() << ":" << now.minute() << "]"
-                   << " (allowed from " << h << ":" << m << ")";
-                logger().debug(ss.str());
+                logger.debug("Reminder - its too early for reminders", " [", now.hour(), ":", now.minute(), "]", " (allowed from ", h, ":", m, ")");
                 return;
             }
         }
@@ -4436,14 +4387,9 @@ void Context::displayReminder() {
     if (!settings_.remind_ends.empty()) {
         int h(0), m(0);
         if (toggl::Formatter::ParseTimeInput(settings_.remind_ends, &h, &m)) {
-            Poco::LocalDateTime end(
-                now.year(), now.month(), now.day(), h, m, now.second());
+            Poco::LocalDateTime end(now.year(), now.month(), now.day(), h, m, now.second());
             if (now > end) {
-                std::stringstream ss;
-                ss << "Reminder - its too late for reminders"
-                   << " [" << now.hour() << ":" << now.minute() << "]"
-                   << " (allowed until " << h << ":" << m << ")";
-                logger().debug(ss.str());
+                logger.debug("Reminder - its too late for reminders", " [", now.hour(), ":", now.minute(), "]", " (allowed until ", h, ":", m, ")");
                 return;
             }
         }
@@ -4578,7 +4524,8 @@ error Context::StartAutotrackerEvent(const TimelineEvent &event) {
         p = user_->related.ProjectByID(rule->PID());
     }
     if (rule->PID() && !p) {
-        return error("autotracker project not found");
+        logger.log(__FUNCTION__, "autotracker project not found");
+        return error::kCannotStartAutotrackerEvent;
     }
 
     Task *t = nullptr;
@@ -4586,11 +4533,13 @@ error Context::StartAutotrackerEvent(const TimelineEvent &event) {
         t = user_->related.TaskByID(rule->TID());
     }
     if (rule->TID() && !t) {
-        return error("autotracker task not found");
+        logger.log(__FUNCTION__, "autotracker task not found");
+        return error::kCannotStartAutotrackerEvent;
     }
 
     if (!p && !t) {
-        return error("no project or task specified in autotracker rule");
+        logger.log(__FUNCTION__, "no project or task specified in autotracker rule");
+        return error::kCannotStartAutotrackerEvent;
     }
 
     UI()->DisplayAutotrackerNotification(p, t);
@@ -4602,7 +4551,7 @@ error Context::CreateCompressedTimelineBatchForUpload(TimelineBatch *batch) {
     try {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("cannot create timeline batch, user logged out");
+            logger.warning("cannot create timeline batch, user logged out");
             return noError;
         }
 
@@ -4661,7 +4610,7 @@ error Context::MarkTimelineBatchAsUploaded(
     try {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("cannot mark timeline events as uploaded, "
+            logger.warning("cannot mark timeline events as uploaded, "
                              "user is already logged out");
             return noError;
         }
@@ -4783,7 +4732,7 @@ void Context::syncerActivity() {
                 err = pushObmAction();
                 if (err != noError) {
                     std::cout << "SYNC: sync-pushObm ERROR\n";
-                    logger().error("Error pushing OBM action: " + err);
+                    logger.error("Error pushing OBM action: ", err);
                 }
 
                 displayError(save(false));
@@ -4810,7 +4759,7 @@ void Context::syncerActivity() {
                 err = pushObmAction();
                 if (err != noError) {
                     std::cout << "SYNC: pushObm ERROR\n";
-                    logger().error("Error pushing OBM action: " + err);
+                    logger.error("Error pushing OBM action: ", err);
                 }
 
                 displayError(save(false));
@@ -4847,7 +4796,7 @@ void Context::onLoadMore(Poco::Util::TimerTask&) {
     }
 
     if (api_token.empty()) {
-        return logger().warning(
+        return logger.warning(
             "cannot load more time entries without API token");
     }
 
@@ -4856,9 +4805,7 @@ void Context::onLoadMore(Poco::Util::TimerTask&) {
         ss << "/api/v9/me/time_entries?since="
            << (Poco::Timestamp() - Poco::Timespan(60, 0, 0, 0, 0)).epochTime();
 
-        std::stringstream l;
-        l << "loading more: " << ss.str();
-        logger().debug(l.str());
+        logger.debug("loading more: ", ss.str());
 
         TogglClient client(UI());
         HTTPSRequest req;
@@ -4869,7 +4816,7 @@ void Context::onLoadMore(Poco::Util::TimerTask&) {
 
         HTTPSResponse resp = client.Get(req);
         if (resp.err != noError) {
-            logger().warning(resp.err);
+            logger.warning(resp.err);
             return;
         }
 
@@ -4882,7 +4829,7 @@ void Context::onLoadMore(Poco::Util::TimerTask&) {
             error err = user_->LoadTimeEntriesFromJSONString(json);
 
             if (err != noError) {
-                logger().error(err);
+                logger.error(err);
                 return;
             }
 
@@ -4899,13 +4846,13 @@ void Context::onLoadMore(Poco::Util::TimerTask&) {
         displayError(save(false));
     }
     catch (const Poco::Exception& exc) {
-        logger().warning(exc.displayText());
+        logger.warning(exc.displayText());
     }
     catch (const std::exception& ex) {
-        logger().warning(ex.what());
+        logger.warning(ex.what());
     }
     catch (const std::string & ex) {
-        logger().warning(ex);
+        logger.warning(ex);
     }
 }
 
@@ -4932,10 +4879,6 @@ void Context::SetLogPath(const std::string &path) {
     log_path_ = path;
 }
 
-Poco::Logger &Context::logger() const {
-    return Poco::Logger::get("context");
-}
-
 error Context::pullAllUserData(
     TogglClient *toggl_client) {
 
@@ -4944,7 +4887,7 @@ error Context::pullAllUserData(
     {
         Poco::Mutex::ScopedLock lock(user_m_);
         if (!user_) {
-            logger().warning("cannot pull user data when logged out");
+            logger.warning("cannot pull user data when logged out");
             return noError;
         }
         api_token = user_->APIToken();
@@ -4954,7 +4897,7 @@ error Context::pullAllUserData(
     }
 
     if (api_token.empty()) {
-        return error("cannot pull user data without API token");
+        return error::kCannotLoadUserDataWithoutApiToken;
     }
 
     try {
@@ -4975,7 +4918,7 @@ error Context::pullAllUserData(
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                return error("cannot load user data when logged out");
+                return error::kCannotLoadUserDataWhenLoggedOut;
             }
             TimeEntry *running_entry = user_->RunningTimeEntry();
 
@@ -5003,16 +4946,13 @@ error Context::pullAllUserData(
         pullUserPreferences(toggl_client);
 
         stopwatch.stop();
-        std::stringstream ss;
-        ss << "User with related data JSON fetched and parsed in "
-           << stopwatch.elapsed() / 1000 << " ms";
-        logger().debug(ss.str());
+        logger.debug("User with related data JSON fetched and parsed in ", stopwatch.elapsed() / 1000, " ms");
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5039,13 +4979,13 @@ error Context::pushChanges(
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("cannot push changes when logged out");
+                logger.warning("cannot push changes when logged out");
                 return noError;
             }
 
             api_token = user_->APIToken();
             if (api_token.empty()) {
-                return error("cannot push changes without API token");
+                return error::kCannotSaveUserDataWithoutApiToken;
             }
 
             collectPushableModels(
@@ -5079,8 +5019,7 @@ error Context::pushChanges(
                 clients,
                 api_token,
                 *toggl_client);
-            if (err != noError &&
-                    err.find(kClientNameAlreadyExists) == std::string::npos) {
+            if (err == error::kClientNameAlreadyExists) {
                 return err;
             }
             client_stopwatch.stop();
@@ -5097,8 +5036,7 @@ error Context::pushChanges(
                 clients,
                 api_token,
                 *toggl_client);
-            if (err != noError &&
-                    err.find(kProjectNameAlready) == std::string::npos) {
+            if (err == error::kProjectNameAlreadyExists) {
                 return err;
             }
 
@@ -5140,13 +5078,13 @@ error Context::pushChanges(
 
         stopwatch.stop();
         ss << ") Total = " << stopwatch.elapsed() / 1000 << " ms";
-        logger().debug(ss.str());
+        logger.debug(ss.str());
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5176,7 +5114,7 @@ error Context::pushClients(
 
         if (resp.err != noError) {
             // if we're able to solve the error
-            if ((*it)->ResolveError(resp.body)) {
+            if ((*it)->ResolveError(Error::fromServerError(resp.body))) {
                 displayError(save(false));
             }
             continue;
@@ -5185,7 +5123,7 @@ error Context::pushClients(
         Json::Value root;
         Json::Reader reader;
         if (!reader.parse(resp.body, root)) {
-            err = error("error parsing client POST response");
+            err = error::kFailedToParseData;
             continue;
         }
 
@@ -5233,7 +5171,7 @@ error Context::pushProjects(
 
         if (resp.err != noError) {
             // if we're able to solve the error
-            if ((*it)->ResolveError(resp.body)) {
+            if ((*it)->ResolveError(Error::fromServerError(resp.body))) {
                 displayError(save(false));
             }
             continue;
@@ -5242,7 +5180,7 @@ error Context::pushProjects(
         Json::Value root;
         Json::Reader reader;
         if (!reader.parse(resp.body, root)) {
-            err = error("error parsing project POST response");
+            err = error::kFailedToParseData;
             continue;
         }
 
@@ -5321,25 +5259,25 @@ error Context::pushEntries(
 
         if (resp.err != noError) {
             // if we're able to solve the error
-            if ((*it)->ResolveError(resp.body)) {
+            if ((*it)->ResolveError(Error::fromServerError(resp.body))) {
                 displayError(save(false));
             }
 
             // Not found on server. Probably deleted already.
-            if ((*it)->isNotFound(resp.body)) {
+            if ((*it)->isNotFound(Error::fromServerError(resp.body))) {
                 (*it)->MarkAsDeletedOnServer();
                 continue;
             }
             error_found = true;
-            error_message = resp.err;
+            error_message = resp.err.String();
             if (resp.status_code == 429) {
-                error_message = error(kRateLimit);
+                error_message = error::kRateLimit;
             }
 
             // Mark the time entry as unsynced now
             (*it)->SetUnsynced();
 
-            offline = IsNetworkingError(resp.err);
+            offline = resp.err.IsNetworkingError();
 
             if (offline) {
                 trigger_sync_ = false;
@@ -5357,12 +5295,12 @@ error Context::pushEntries(
         Json::Value root;
         Json::Reader reader;
         if (!reader.parse(resp.body, root)) {
-            return error("error parsing time entry POST response");
+            return error::kFailedToParseData;
         }
 
         auto id = root["id"].asUInt64();
         if (!id) {
-            logger().error("Backend is sending invalid data: ignoring update without an ID");
+            logger.error("Backend is sending invalid data: ignoring update without an ID");
             continue;
         }
 
@@ -5373,14 +5311,14 @@ error Context::pushEntries(
         }
 
         if ((*it)->ID() != id) {
-            return error("Backend has changed the ID of the entry");
+            return error::kBackendChangedTheID;
         }
 
         (*it)->LoadFromJSON(root);
     }
 
     if (error_found) {
-        return error_message;
+        return error::REMOVE_LATER_NETWORK_RESPONSE;
     }
     return noError;
 }
@@ -5388,17 +5326,17 @@ error Context::pushEntries(
 error Context::pullObmExperiments() {
     try {
         if (HTTPSClient::Config.OBMExperimentNrs.empty()) {
-            logger().debug("No OBM experiment enabled by UI");
+            logger.debug("No OBM experiment enabled by UI");
             return noError;
         }
 
-        logger().trace("Fetching OBM experiments from backend");
+        logger.trace("Fetching OBM experiments from backend");
 
         std::string apitoken("");
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot fetch OBM experiments without user");
+                logger.warning("Cannot fetch OBM experiments without user");
                 return noError;
             }
             apitoken = user_->APIToken();
@@ -5419,13 +5357,13 @@ error Context::pullObmExperiments() {
         Json::Value json;
         Json::Reader reader;
         if (!reader.parse(resp.body, json)) {
-            return error("Error in OBM experiments response body");
+            return error::kFailedToParseData;
         }
 
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("Cannot apply OBM experiments without user");
+                logger.warning("Cannot apply OBM experiments without user");
                 return noError;
             }
             user_->LoadObmExperiments(json);
@@ -5433,11 +5371,11 @@ error Context::pullObmExperiments() {
 
         return noError;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 }
 
@@ -5452,7 +5390,7 @@ error Context::pushObmAction() {
         {
             Poco::Mutex::ScopedLock lock(user_m_);
             if (!user_) {
-                logger().warning("cannot push changes when logged out");
+                logger.warning("cannot push changes when logged out");
                 return noError;
             }
 
@@ -5462,7 +5400,7 @@ error Context::pushObmAction() {
 
             req.basic_auth_username = user_->APIToken();
             if (req.basic_auth_username.empty()) {
-                return error("cannot push OBM actions without API token");
+                return error::kCannotSaveUserDataWithoutApiToken;
             }
 
             // find action that has not been uploaded yet
@@ -5486,7 +5424,7 @@ error Context::pushObmAction() {
             req.payload = Json::StyledWriter().write(root);
         }
 
-        logger().debug(req.payload);
+        logger.debug(req.payload);
 
         TogglClient toggl_client;
         HTTPSResponse resp = toggl_client.Post(req);
@@ -5502,11 +5440,11 @@ error Context::pushObmAction() {
         for_upload->MarkAsDeletedOnServer();
         for_upload->Delete();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5519,11 +5457,7 @@ error Context::me(
     const Poco::Int64 since) {
 
     if (email.empty()) {
-        return "Empty email or API token";
-    }
-
-    if (password.empty()) {
-        return "Empty password";
+        return error::kMissingArgument;
     }
 
     try {
@@ -5551,11 +5485,11 @@ error Context::me(
 
         *user_data_json = resp.body;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5575,8 +5509,8 @@ bool Context::canChangeProjectTo(TimeEntry* te, Project* p) {
 }
 
 error Context::logAndDisplayUserTriedEditingLockedEntry() {
-    logger().warning("User tried editing locked time entry");
-    return displayError(error("Cannot change locked time entry"));
+    logger.warning("User tried editing locked time entry");
+    return displayError(error::kCannotChangeLockedTE);
 }
 
 bool Context::isTimeLockedInWorkspace(time_t t, Workspace* ws) {
@@ -5596,26 +5530,23 @@ error Context::pullWorkspaces(TogglClient* toggl_client) {
     std::string api_token = user_->APIToken();
 
     if (api_token.empty()) {
-        return error("cannot pull user data without API token");
+        return error::kCannotLoadUserDataWithoutApiToken;
     }
 
     std::string json("");
 
     try {
-        std::stringstream ss;
-        ss << "/api/v9/me/workspaces";
-
         HTTPSRequest req;
         req.host = urls::API();
-        req.relative_url = ss.str();
+        req.relative_url = "/api/v9/me/workspaces";
         req.basic_auth_username = api_token;
         req.basic_auth_password = "api_token";
 
         HTTPSResponse resp = toggl_client->Get(req);
         if (resp.err != noError) {
-            if (resp.err.find(kForbiddenError) != std::string::npos) {
+            if (resp.err == error::kForbiddenError) {
                 // User has no workspaces
-                return error(kMissingWS); // NOLINT
+                return error::kMissingWS; // NOLINT
             }
             return resp.err;
         }
@@ -5626,13 +5557,13 @@ error Context::pullWorkspaces(TogglClient* toggl_client) {
 
     }
     catch (const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5641,7 +5572,7 @@ error Context::pullWorkspacePreferences(TogglClient* toggl_client) {
     std::vector<Workspace*> workspaces;
     {
         Poco::Mutex::ScopedLock lock(user_m_);
-        logger().debug("user mutex lock success - c:pullWorkspacePreferences");
+        logger.debug("user mutex lock success - c:pullWorkspacePreferences");
 
         user_->related.WorkspaceList(&workspaces);
     }
@@ -5667,7 +5598,7 @@ error Context::pullWorkspacePreferences(TogglClient* toggl_client) {
         Json::Value root;
         Json::Reader reader;
         if (!reader.parse(json, root)) {
-            return error("Failed to load workspace preferences");
+            return error::kFailedToParseData;
         }
 
         ws->LoadSettingsFromJson(root);
@@ -5684,7 +5615,7 @@ error Context::pullWorkspacePreferences(
     std::string api_token = user_->APIToken();
 
     if (api_token.empty()) {
-        return error("cannot pull user data without API token");
+        return error::kCannotLoadUserDataWithoutApiToken;
     }
 
     try {
@@ -5707,13 +5638,13 @@ error Context::pullWorkspacePreferences(
         *json = resp.body;
     }
     catch (const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5723,17 +5654,15 @@ error Context::pullUserPreferences(
     std::string api_token = user_->APIToken();
 
     if (api_token.empty()) {
-        return error("cannot pull user data without API token");
+        return error::kCannotLoadUserDataWithoutApiToken;
     }
 
     try {
         std::string json("");
-        std::stringstream ss;
-        ss << "/api/v9/me/preferences/desktop";
 
         HTTPSRequest req;
         req.host = urls::API();
-        req.relative_url = ss.str();
+        req.relative_url = "/api/v9/me/preferences/desktop";
         req.basic_auth_username = api_token;
         req.basic_auth_password = "api_token";
 
@@ -5750,7 +5679,7 @@ error Context::pullUserPreferences(
         Json::Value root;
         Json::Reader reader;
         if (!reader.parse(json, root)) {
-            return error("Failed to load user preferences");
+            return error::kFailedToParseData;
         }
 
         if (user_->LoadUserPreferencesFromJSON(root)) {
@@ -5768,13 +5697,13 @@ error Context::pullUserPreferences(
         }
     }
     catch (const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5809,8 +5738,9 @@ error Context::signupGoogle(
 
         HTTPSResponse resp = toggl_client->Post(req);
         if (resp.err != noError) {
-            if (kBadRequestError == resp.err) {
-                return resp.body;
+            if (resp.err == error::kBadRequestError) {
+                //return resp.body;
+                return error::REMOVE_LATER_NETWORK_RESPONSE;
             }
             return resp.err;
         }
@@ -5818,13 +5748,13 @@ error Context::signupGoogle(
         *user_data_json = resp.body;
     }
     catch (const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     catch (const std::string& ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5837,11 +5767,11 @@ error Context::signup(
     const uint64_t country_id) {
 
     if (email.empty()) {
-        return "Empty email";
+        return error::kEmptyEmail;
     }
 
     if (password.empty()) {
-        return "Empty password";
+        return error::kEmptyPassword;
     }
 
     try {
@@ -5867,25 +5797,26 @@ error Context::signup(
 
         HTTPSResponse resp = toggl_client->Post(req);
         if (resp.err != noError) {
-            if (kBadRequestError == resp.err) {
-                return resp.body;
+            if (resp.err == error::kBadRequestError) {
+                //return resp.body;
+                return error::REMOVE_LATER_NETWORK_RESPONSE;
             }
             return resp.err;
         }
 
         *user_data_json = resp.body;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
 
 void Context::OpenTimelineDataView() {
-    logger().debug("OpenTimelineDataView");
+    logger.debug("OpenTimelineDataView");
 
     UI()->SetTimelineDateAt(Poco::LocalDateTime());
 
@@ -5933,7 +5864,7 @@ error Context::ToSAccept() {
     std::string api_token = user_->APIToken();
 
     if (api_token.empty()) {
-        return error("cannot pull user data without API token");
+        return error::kMissingApiToken;
     }
 
     TogglClient toggl_client(UI());
@@ -5951,14 +5882,14 @@ error Context::ToSAccept() {
         overlay_visible_ = false;
         OpenTimeEntryList();
     } catch(const Poco::Exception& exc) {
-        displayError(kCannotConnectError);
-        return exc.displayText();
+        displayError(error::kCannotConnectError);
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        displayError(kCannotConnectError);
-        return ex.what();
+        displayError(error::kCannotConnectError);
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        displayError(kCannotConnectError);
-        return ex;
+        displayError(error::kCannotConnectError);
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -5992,7 +5923,7 @@ error Context::PullCountries() {
         Json::Reader reader;
 
         if (!reader.parse(resp.body, root)) {
-            return error("Error parsing countries response body");
+            return error::kFailedToParseData;
         }
 
         std::vector<TogglCountryView> countries;
@@ -6007,11 +5938,11 @@ error Context::PullCountries() {
 
         //country_item_clear(first);
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
diff --git a/src/context.h b/src/context.h
index 9607663125..86fb859110 100644
--- a/src/context.h
+++ b/src/context.h
@@ -16,6 +16,7 @@
 #include "gui.h"
 #include "help_article.h"
 #include "idle.h"
+#include "util/logger.h"
 #include "model_change.h"
 #include "timeline_event.h"
 #include "timeline_notifications.h"
@@ -529,7 +530,7 @@ class TOGGL_INTERNAL_EXPORT Context : public TimelineDatasource {
     static void parseVersion(int result[4], const std::string& input);
     static bool lessThanVersion(const std::string& version1, const std::string& version2);
 
-    Poco::Logger &logger() const;
+    Logger logger { "context" };
 
     void sync(const bool full_sync);
 
@@ -585,6 +586,7 @@ class TOGGL_INTERNAL_EXPORT Context : public TimelineDatasource {
     void updateUI(const UIElements &elements);
 
     error displayError(const error &err);
+    error displayError(const std::string &err, bool is_user_error = false);
 
     void scheduleSync();
 
diff --git a/src/database.cc b/src/database.cc
index 9ac5708814..7bfc0d3771 100644
--- a/src/database.cc
+++ b/src/database.cc
@@ -29,7 +29,6 @@
 #include <Poco/Data/SQLite/Utility.h>
 #include <Poco/Data/Statement.h>
 #include <Poco/FileStream.h>
-#include <Poco/Logger.h>
 #include <Poco/Stopwatch.h>
 #include <Poco/StreamCopier.h>
 #include <Poco/UUID.h>
@@ -53,37 +52,31 @@ Database::Database(const std::string &db_path)
     {
         int is_sqlite_threadsafe = Poco::Data::SQLite::Utility::isThreadSafe();
 
-        std::stringstream ss;
-        ss << "sqlite3_threadsafe()=" << is_sqlite_threadsafe;
-        logger().debug(ss.str());
+        logger.debug("sqlite3_threadsafe()=", is_sqlite_threadsafe);
 
         if (!is_sqlite_threadsafe) {
-            logger().error("Database is not thread safe!");
+            logger.error("Database is not thread safe!");
             return;
         }
     }
 
     error err = setJournalMode("wal");
     if (err != noError) {
-        logger().error("Failed to set journal mode to wal!");
+        logger.error("Failed to set journal mode to wal!");
         return;
     }
 
     std::string mode("");
     err = journalMode(&mode);
     if (err != noError) {
-        logger().error("Could not detect journal mode!");
+        logger.error("Could not detect journal mode!");
         return;
     }
 
-    {
-        std::stringstream ss;
-        ss << "PRAGMA journal_mode=" << mode;
-        logger().debug(ss.str());
-    }
+    logger.debug("PRAGMA journal_mode=", mode);
 
     if ("wal" != mode) {
-        logger().error("Failed to enable wal journal mode!");
+        logger.error("Failed to enable wal journal mode!");
         return;
     }
 
@@ -97,7 +90,7 @@ Database::Database(const std::string &db_path)
         "time_entries", start.timestamp());
 
     if (err != noError) {
-        logger().error("failed to clean Up Time Entries Data: " + err);
+        logger.error("failed to clean Up Time Entries Data: " + err.String());
         // but will continue, its not vital
     }
 
@@ -109,13 +102,13 @@ Database::Database(const std::string &db_path)
         timeline_start.timestamp());
 
     if (err != noError) {
-        logger().error("failed to clean Up Timeline Events Data: " + err);
+        logger.error("failed to clean Up Timeline Events Data: " + err.String());
         // but will continue, its not vital
     }
 
     err = vacuum();
     if (err != noError) {
-        logger().error("failed to vacuum: " + err);
+        logger.error("failed to vacuum: " + err.String());
         // but will continue, its not vital
     }
 
@@ -124,19 +117,14 @@ Database::Database(const std::string &db_path)
 
     err = initialize_tables();
     if (err != noError) {
-        logger().error(err);
+        logger.error(err);
         // We're doomed now; cannot continue without a DB
         throw(err);
     }
 
     stopwatch.stop();
 
-    {
-        std::stringstream ss;
-        ss  << "Migrated in "
-            << stopwatch.elapsed() / 1000 << " ms";
-        logger().debug(ss.str());
-    }
+    logger.debug("Migrated in ", stopwatch.elapsed() / 1000, " ms");
 }
 
 Database::~Database() {
@@ -211,12 +199,8 @@ error Database::deleteAllFromTableByUID(
     const std::string &table_name,
     const Poco::UInt64 &UID) {
 
-
-    if (!UID) {
-        return error("Cannot delete user data without user ID");
-    }
-    if (table_name.empty()) {
-        return error("Cannot delete from table without table name");
+    if (!UID || table_name.empty()) {
+        return error::kMissingArgument;
     }
 
     try {
@@ -229,11 +213,11 @@ error Database::deleteAllFromTableByUID(
                   useRef(UID),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("deleteAllFromTableByUID");
 }
@@ -243,7 +227,7 @@ error Database::deleteAllFromTableByDate(
     const Poco::Timestamp &time) {
 
     if (table_name.empty()) {
-        return error("Cannot delete from table without table name");
+        return error::kMissingArgument;
     }
 
     const Poco::Int64 stopTime = time.epochTime();
@@ -259,11 +243,11 @@ error Database::deleteAllFromTableByDate(
                   useRef(stopTime),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("deleteAllFromTableByDate");
 }
@@ -283,11 +267,11 @@ error Database::deleteAllSyncedTimelineEventsByDate(
                   useRef(endTime),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("deleteAllSyncedTimelineEventsByDate");
 }
@@ -305,18 +289,18 @@ error Database::journalMode(std::string *mode) {
                   into(*mode),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("journalMode");
 }
 
 error Database::setJournalMode(const std::string &mode) {
     if (mode.empty()) {
-        return error("Cannot set journal mode without a mode");
+        return error::kMissingArgument;
     }
 
 
@@ -328,11 +312,11 @@ error Database::setJournalMode(const std::string &mode) {
                   "PRAGMA journal_mode=" << mode,
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("setJournalMode");
 }
@@ -345,36 +329,28 @@ error Database::vacuum() {
         *session_ <<
                   "VACUUM;" << now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("vacuum");
 }
 
-Poco::Logger &Database::logger() const {
-    return Poco::Logger::get("database");
-}
-
 error Database::DeleteFromTable(
     const std::string &table_name,
     const Poco::Int64 &local_id) {
 
     if (table_name.empty()) {
-        return error("Cannot delete from table without table name");
+        return error::kMissingArgument;
     }
 
     if (!local_id) {
         return noError;
     }
 
-
-    std::stringstream ss;
-    ss << "Deleting from table " << table_name
-       << ", local ID: " << local_id;
-    logger().debug(ss.str());
+    logger.debug( "Deleting from table ", table_name, ", local ID: ", local_id);
 
     try {
         Poco::Mutex::ScopedLock lock(session_m_);
@@ -386,11 +362,11 @@ error Database::DeleteFromTable(
                   useRef(local_id),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("DeleteFromTable");
 }
@@ -402,7 +378,8 @@ error Database::last_error(const std::string &was_doing) {
 
     std::string last = Poco::Data::SQLite::Utility::lastError(*session_);
     if (last != "not an error" && last != "unknown error") {
-        return error(was_doing + ": " + last);
+        //return error(was_doing + ": " + last);
+        return error::REMOVE_LATER_DATABASE_LAST_ERROR;
     }
     return noError;
 }
@@ -416,7 +393,7 @@ std::string Database::GenerateGUID() {
 error Database::LoadCurrentUser(User *user) {
     poco_check_ptr(user);
 
-    logger().debug("LoadCurrentUser");
+    logger.debug("LoadCurrentUser");
 
     std::string api_token("");
     Poco::UInt64 uid(0);
@@ -485,11 +462,11 @@ error Database::LoadSettings(Settings *settings) {
                   limit(1),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("LoadSettings");
 }
@@ -517,11 +494,11 @@ error Database::SaveWindowSettings(
                   useRef(window_width),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 
     return last_error("SaveWindowSettings");
@@ -579,11 +556,11 @@ error Database::LoadWindowSettings(
         *window_height = height;
         *window_width = width;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("LoadWindowSettings");
 }
@@ -617,11 +594,11 @@ error Database::LoadProxySettings(
         proxy->SetUsername(username);
         proxy->SetPassword(password);
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("LoadProxySettings");
 }
@@ -741,11 +718,11 @@ error Database::SetSettingsRemindTimes(
                   useRef(remind_ends),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 
     return last_error("SetSettingsRemindTimes");
@@ -783,11 +760,11 @@ error Database::SetSettingsRemindDays(
                   useRef(remind_sun),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 
     return last_error("SetSettingsRemindDays");
@@ -888,11 +865,11 @@ error Database::setSettingsValue(
                   useRef(value),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("setSettingsValue");
 }
@@ -914,11 +891,11 @@ error Database::getSettingsValue(
                   limit(1),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("getSettingsValue");
 }
@@ -973,11 +950,11 @@ error Database::SaveProxySettings(
                   useRef(proxy.Password()),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("SaveProxySettings");
 }
@@ -998,11 +975,11 @@ error Database::Trim(const std::string &text, std::string *result) {
                   limit(1),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("Trim");
 }
@@ -1028,11 +1005,11 @@ error Database::ResetWindow() {
                   "mini_timer_w = 0",
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("ResetWindow");
 }
@@ -1052,11 +1029,11 @@ error Database::LoadUpdateChannel(
                   limit(1),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("LoadUpdateChannel");
 }
@@ -1067,7 +1044,7 @@ error Database::SaveUpdateChannel(
     if (update_channel != "stable" &&
             update_channel != "beta" &&
             update_channel != "dev") {
-        return error("Invalid update channel");
+        return error::kInvalidUpdateChannel;
     }
 
     return setSettingsValue("update_channel", update_channel);
@@ -1078,7 +1055,7 @@ error Database::LoadUserByEmail(
     User *model) {
 
     if (email.empty()) {
-        return error("Cannot load user by email token without an email");
+        return error::kMissingArgument;
     }
 
     Poco::UInt64 uid(0);
@@ -1108,11 +1085,11 @@ error Database::LoadUserByEmail(
             return noError;
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return LoadUserByID(uid, model);
 }
@@ -1176,7 +1153,7 @@ error Database::LoadUserByID(
     User *user) {
 
     if (!UID) {
-        return error("Cannot load user by ID without an ID");
+        return error::kMissingArgument;
     }
 
     Poco::Stopwatch stopwatch;
@@ -1253,11 +1230,11 @@ error Database::LoadUserByID(
         user->SetDefaultTID(default_tid);
         user->SetCollapseEntries(collapse_entries);
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     error err = loadUsersRelatedData(user);
     if (err != noError) {
@@ -1265,9 +1242,7 @@ error Database::LoadUserByID(
     }
 
     stopwatch.stop();
-    std::stringstream ss;
-    ss << "User loaded in " << stopwatch.elapsed() / 1000 << " ms";
-    logger().debug(ss.str());
+    logger.debug("User loaded in ", stopwatch.elapsed() / 1000, " ms");
 
     return noError;
 }
@@ -1277,7 +1252,7 @@ error Database::loadWorkspaces(
     std::vector<Workspace *> *list) {
 
     if (!UID) {
-        return error("Cannot load user workspaces without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1323,11 +1298,11 @@ error Database::loadWorkspaces(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadWorkspaces");
 }
@@ -1337,7 +1312,7 @@ error Database::loadClients(
     std::vector<Client *> *list) {
 
     if (!UID) {
-        return error("Cannot load user clients without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1385,11 +1360,11 @@ error Database::loadClients(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadClients");
 }
@@ -1399,7 +1374,7 @@ error Database::loadProjects(
     std::vector<Project *> *list) {
 
     if (!UID) {
-        return error("Cannot load user projects without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1475,11 +1450,11 @@ error Database::loadProjects(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadProjects");
 }
@@ -1489,7 +1464,7 @@ error Database::loadTasks(
     std::vector<Task *> *list) {
 
     if (!UID) {
-        return error("Cannot load user tasks without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1537,11 +1512,11 @@ error Database::loadTasks(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadTasks");
 }
@@ -1551,7 +1526,7 @@ error Database::loadTags(
     std::vector<Tag *> *list) {
 
     if (!UID) {
-        return error("Cannot load user tags without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1598,11 +1573,11 @@ error Database::loadTags(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadTags");
 }
@@ -1612,7 +1587,7 @@ error Database::loadAutotrackerRules(
     std::vector<AutotrackerRule *> *list) {
 
     if (!UID) {
-        return error("Cannot load autotracker rules without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1652,11 +1627,11 @@ error Database::loadAutotrackerRules(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadAutotrackerRules");
 }
@@ -1666,7 +1641,7 @@ error Database::loadObmActions(
     std::vector<ObmAction *> *list) {
 
     if (!UID) {
-        return error("Cannot load OBM actions without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1704,11 +1679,11 @@ error Database::loadObmActions(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadObmActions");
 }
@@ -1718,7 +1693,7 @@ error Database::loadObmExperiments(
     std::vector<ObmExperiment *> *list) {
 
     if (!UID) {
-        return error("Cannot load OBM experiments without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1757,11 +1732,11 @@ error Database::loadObmExperiments(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("loadObmExperiments");
 }
@@ -1771,7 +1746,7 @@ error Database::loadTimelineEvents(
     std::vector<TimelineEvent *> *list) {
 
     if (!UID) {
-        return error("Cannot load user timeline without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1833,11 +1808,11 @@ error Database::loadTimelineEvents(
             model->EnsureGUID();
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -1847,7 +1822,7 @@ error Database::loadTimeEntries(
     std::vector<TimeEntry *> *list) {
 
     if (!UID) {
-        return error("Cannot load user time entries without an user ID");
+        return error::kMissingArgument;
     }
 
     try {
@@ -1887,11 +1862,11 @@ error Database::loadTimeEntries(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -1974,9 +1949,9 @@ error Database::loadTimeEntriesFromSQLStatement(
                     model->SetProjectGUID(rs[18].convert<std::string>());
                 }
                 if (rs[19].isEmpty()) {
-                    model->SetValidationError("");
+                    model->SetValidationError(error::kNoError);
                 } else {
-                    model->SetValidationError(rs[19].convert<std::string>());
+                    model->SetValidationError(error::fromString(rs[19].convert<std::string>()));
                 }
                 model->ClearDirty();
 
@@ -1985,11 +1960,11 @@ error Database::loadTimeEntriesFromSQLStatement(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2002,7 +1977,7 @@ error Database::saveRelatedModels(
     std::vector<ModelChange> *changes) {
 
     if (!UID) {
-        return error("Cannot save user related data without an user ID");
+        return error::kMissingArgument;
     }
 
     poco_check_ptr(list);
@@ -2059,9 +2034,6 @@ error Database::saveModel(
         // Time entries need to have a GUID,
         // we expect it everywhere in the UI
         model->EnsureGUID();
-        if (model->GUID().empty()) {
-            return error("Cannot save time entry without a GUID");
-        }
 
         if (!model->NeedsToBeSaved()) {
             return noError;
@@ -2071,10 +2043,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating time entry " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().debug(ss.str());
+            logger.debug("Updating time entry ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             if (model->ID()) {
                 *session_ <<
@@ -2109,7 +2078,7 @@ error Database::saveModel(
                           useRef(model->DeletedAt()),
                           useRef(model->UpdatedAt()),
                           useRef(model->ProjectGUID()),
-                          useRef(model->ValidationError()),
+                          model->ValidationError().String(),
                           useRef(model->LocalID()),
                           now;
             } else {
@@ -2144,7 +2113,7 @@ error Database::saveModel(
                           useRef(model->DeletedAt()),
                           useRef(model->UpdatedAt()),
                           useRef(model->ProjectGUID()),
-                          useRef(model->ValidationError()),
+                          model->ValidationError().String(),
                           useRef(model->LocalID()),
                           now;
             }
@@ -2166,10 +2135,7 @@ error Database::saveModel(
                     model->GUID()));
             }
         } else {
-            std::stringstream ss;
-            ss << "Inserting time entry " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().debug(ss.str());
+            logger.debug("Inserting time entry ", model->String(), " in thread ", Poco::Thread::currentTid());
             if (model->ID()) {
                 *session_ <<
                           "insert into time_entries(id, uid, description, "
@@ -2202,7 +2168,7 @@ error Database::saveModel(
                           useRef(model->DeletedAt()),
                           useRef(model->UpdatedAt()),
                           useRef(model->ProjectGUID()),
-                          useRef(model->ValidationError()),
+                          model->ValidationError().String(),
                           now;
             } else {
                 *session_ <<
@@ -2236,7 +2202,7 @@ error Database::saveModel(
                           useRef(model->DeletedAt()),
                           useRef(model->UpdatedAt()),
                           useRef(model->ProjectGUID()),
-                          useRef(model->ValidationError()),
+                          model->ValidationError().String(),
                           now;
             }
             error err = last_error("saveTimeEntry");
@@ -2261,11 +2227,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2300,23 +2266,23 @@ error Database::saveModel(
         }
 
         if (!model->UID()) {
-            return error("Cannot save timeline event without an user ID");
+            //return error("Cannot save timeline event without an user ID");
+            return error::REMOVE_LATER_DATABASE_STORE_ERROR;
         }
         if (!model->Start()) {
-            return error("Cannot save timeline event without start time");
+            //return error("Cannot save timeline event without start time");
+            return error::REMOVE_LATER_DATABASE_STORE_ERROR;
         }
         if (!model->EndTime()) {
-            return error("Cannot save timeline event without end time");
+            //return error("Cannot save timeline event without end time");
+            return error::REMOVE_LATER_DATABASE_STORE_ERROR;
         }
 
         Poco::Int64 start_time(model->Start());
         Poco::Int64 end_time(model->EndTime());
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating timeline event " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating timeline event ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update timeline_events set "
@@ -2360,10 +2326,7 @@ error Database::saveModel(
                     model->GUID()));
             }
         } else {
-            std::stringstream ss;
-            ss << "Inserting timeline event " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting timeline event ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "insert into timeline_events("
@@ -2420,11 +2383,11 @@ error Database::saveModel(
 
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2444,10 +2407,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating autotracker rule " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating autotracker rule ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update autotracker_settings set "
@@ -2479,10 +2439,7 @@ error Database::saveModel(
             }
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting autotracker rule " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting autotracker rule ", model->String(), " in thread ", Poco::Thread::currentTid());
             *session_ <<
                       "insert into autotracker_settings(uid, term, pid, tid) "
                       "values(:uid, :term, :pid, :tid)",
@@ -2514,11 +2471,11 @@ error Database::saveModel(
 
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2538,10 +2495,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating OBM action " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating OBM action ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update obm_actions set "
@@ -2575,10 +2529,7 @@ error Database::saveModel(
             }
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting OBM action " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting OBM action ", model->String(), " in thread ", Poco::Thread::currentTid());
             *session_ <<
                       "insert into obm_actions(uid, experiment_id, key, value) "
                       "values(:uid, :experiment_id, :key, :value)",
@@ -2610,11 +2561,11 @@ error Database::saveModel(
 
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2635,10 +2586,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating workspace " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating workspace ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update workspaces set "
@@ -2669,10 +2617,7 @@ error Database::saveModel(
                 model->ModelName(), kChangeTypeUpdate, model->ID(), ""));
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting workspace " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting workspace ", model->String(), " in thread ", Poco::Thread::currentTid());
             *session_ <<
                       "insert into workspaces(id, uid, name, premium, "
                       "only_admins_may_create_projects, admin, "
@@ -2711,11 +2656,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2733,7 +2678,8 @@ error Database::saveModel(
         if (!model->ID()) {
             model->EnsureGUID();
             if (model->GUID().empty()) {
-                return error("Cannot save new cient without a GUID");
+                //return error("Cannot save new cient without a GUID");
+                return error::REMOVE_LATER_DATABASE_STORE_ERROR;
             }
         }
 
@@ -2745,10 +2691,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating client " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating client ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             if (model->GUID().empty()) {
                 *session_ <<
@@ -2786,10 +2729,7 @@ error Database::saveModel(
                 model->GUID()));
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting client " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting client ", model->String(), " in thread ", Poco::Thread::currentTid());
             if (model->GUID().empty()) {
                 *session_ <<
                           "insert into clients(id, uid, name, wid) "
@@ -2832,11 +2772,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -2854,7 +2794,8 @@ error Database::saveModel(
         if (!model->ID()) {
             model->EnsureGUID();
             if (model->GUID().empty()) {
-                return error("Cannot save project without a GUID");
+                //return error("Cannot save project without a GUID");
+                return error::REMOVE_LATER_DATABASE_STORE_ERROR;
             }
         }
 
@@ -2866,10 +2807,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating project " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().debug(ss.str());
+            logger.debug("Updating project ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             if (model->ID()) {
                 if (model->GUID().empty()) {
@@ -2964,10 +2902,7 @@ error Database::saveModel(
                 model->GUID()));
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting project " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().debug(ss.str());
+            logger.debug("Inserting project ", model->String(), " in thread ", Poco::Thread::currentTid());
             if (model->ID()) {
                 if (model->GUID().empty()) {
                     *session_ <<
@@ -3079,11 +3014,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -3103,10 +3038,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating task " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating task ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update tasks set "
@@ -3129,10 +3061,7 @@ error Database::saveModel(
                 model->ModelName(), kChangeTypeUpdate, model->ID(), ""));
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting task " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting task ", model->String(), " in thread ", Poco::Thread::currentTid());
             *session_ <<
                       "insert into tasks(id, uid, name, wid, pid, active) "
                       "values(:id, :uid, :name, :wid, :pid, :active)",
@@ -3162,11 +3091,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -3186,10 +3115,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating tag " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating tag ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             if (model->GUID().empty()) {
                 *session_ <<
@@ -3227,10 +3153,7 @@ error Database::saveModel(
                 model->GUID()));
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting tag " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting tag ", model->String(), " in thread ", Poco::Thread::currentTid());
             if (model->GUID().empty()) {
                 *session_ <<
                           "insert into tags(id, uid, name, wid) "
@@ -3273,11 +3196,11 @@ error Database::saveModel(
         }
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -3291,7 +3214,7 @@ error Database::SaveUser(
 
     // Do nothing, if user has already logged out
     if (!user) {
-        logger().warning("Cannot save user, user is logged out");
+        logger.warning("Cannot save user, user is logged out");
         return noError;
     }
 
@@ -3302,13 +3225,16 @@ error Database::SaveUser(
     stopwatch.start();
 
     if (user->Email().empty()) {
-        return error("Missing user e-mail, cannot save user");
+        //return error("Missing user e-mail, cannot save user");
+        return error::REMOVE_LATER_DATABASE_STORE_ERROR;
     }
     if (user->APIToken().empty()) {
-        return error("Missing user API token, cannot save user");
+        //return error("Missing user API token, cannot save user");
+        return error::REMOVE_LATER_DATABASE_STORE_ERROR;
     }
     if (!user->ID()) {
-        return error("Missing user ID, cannot save user");
+        //return error("Missing user ID, cannot save user");
+        return error::REMOVE_LATER_DATABASE_STORE_ERROR;
     }
 
     session_->begin();
@@ -3319,10 +3245,7 @@ error Database::SaveUser(
     if (!user->LocalID() || user->Dirty()) {
         try {
             if (user->LocalID()) {
-                std::stringstream ss;
-                ss << "Updating user " + user->String()
-                   << " in thread " << Poco::Thread::currentTid();
-                logger().trace(ss.str());
+                logger.trace("Updating user ", user->String(), " in thread ", Poco::Thread::currentTid());
 
                 *session_ <<
                           "update users set "
@@ -3361,10 +3284,7 @@ error Database::SaveUser(
                 changes->push_back(ModelChange(
                     user->ModelName(), kChangeTypeUpdate, user->ID(), ""));
             } else {
-                std::stringstream ss;
-                ss << "Inserting user " + user->String()
-                   << " in thread " << Poco::Thread::currentTid();
-                logger().trace(ss.str());
+                logger.trace("Inserting user ", user->String(), " in thread ", Poco::Thread::currentTid());
                 *session_ <<
                           "insert into users("
                           "id, default_wid, since, fullname, email, "
@@ -3416,13 +3336,13 @@ error Database::SaveUser(
             user->ClearDirty();
         } catch(const Poco::Exception& exc) {
             session_->rollback();
-            return exc.displayText();
+            return error::REMOVE_LATER_EXCEPTION_HANDLER;
         } catch(const std::exception& ex) {
             session_->rollback();
-            return ex.what();
+            return error::REMOVE_LATER_EXCEPTION_HANDLER;
         } catch(const std::string & ex) {
             session_->rollback();
-            return ex;
+            return error::REMOVE_LATER_EXCEPTION_HANDLER;
         }
     }
 
@@ -3576,13 +3496,7 @@ error Database::SaveUser(
 
     stopwatch.stop();
 
-    {
-        std::stringstream ss;
-        ss  << "User with_related_data=" << with_related_data << " saved in "
-            << stopwatch.elapsed() / 1000 << " ms in thread "
-            << Poco::Thread::currentTid();
-        logger().debug(ss.str());
-    }
+    logger.debug("User with_related_data=", with_related_data, " saved in ", stopwatch.elapsed() / 1000, " ms in thread ", Poco::Thread::currentTid());
 
     return noError;
 }
@@ -3663,11 +3577,11 @@ error Database::CurrentAPIToken(
                   limit(1),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("CurrentAPIToken");
 }
@@ -3681,11 +3595,11 @@ error Database::ClearCurrentAPIToken() {
         *session_ <<
                   "delete from sessions", now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("ClearCurrentAPIToken");
 }
@@ -3696,11 +3610,8 @@ error Database::SetCurrentAPIToken(
     try {
         Poco::Mutex::ScopedLock lock(session_m_);
 
-        if (token.empty()) {
-            return error("cannot start session without API token");
-        }
-        if (!uid) {
-            return error("cannot start session without user ID");
+        if (token.empty() || !uid) {
+            return error::kMissingArgument;
         }
 
         poco_check_ptr(session_);
@@ -3717,11 +3628,11 @@ error Database::SetCurrentAPIToken(
                   useRef(uid),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("SetCurrentAPIToken");
 }
@@ -3760,11 +3671,11 @@ error Database::EnsureTimelineGUIDS() {
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 }
 
@@ -3819,11 +3730,11 @@ error Database::saveAnalyticsClientID() {
                   useRef(analytics_client_id_),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("saveAnalyticsClientID");
 }
@@ -3856,11 +3767,11 @@ error Database::LoadMigrations(
             }
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("LoadMigrations");
 }
@@ -3869,11 +3780,8 @@ error Database::Migrate(
     const std::string &name,
     const std::string &sql) {
 
-    if (name.empty()) {
-        return error("Cannot run a migration without name");
-    }
-    if (sql.empty()) {
-        return error("Cannot run a migration without SQL");
+    if (name.empty() || sql.empty()) {
+        return error::kMissingArgument;
     }
 
     try {
@@ -3896,11 +3804,7 @@ error Database::Migrate(
             return noError;
         }
 
-        std::stringstream ss;
-        ss  << "Migrating" << "\n"
-            << name << "\n"
-            << sql << "\n";
-        logger().debug(ss.str());
+        logger.debug("Migrating", "\n", name, "\n", sql, "\n");
 
         err = execute(sql);
         if (err != noError) {
@@ -3916,21 +3820,18 @@ error Database::Migrate(
             return err;
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
 
-error Database::execute(
-    const std::string &sql) {
-
-
+error Database::execute(const std::string &sql) {
     if (sql.empty()) {
-        return error("Cannot execute empty SQL");
+        return error::kMissingArgument;
     }
 
     try {
@@ -3944,11 +3845,11 @@ error Database::execute(
             return err;
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -3958,7 +3859,7 @@ error Database::String(
     std::string *result) {
 
     if (sql.empty()) {
-        return error("Cannot select from database with empty SQL");
+        return error::kMissingArgument;
     }
 
     try {
@@ -3973,21 +3874,18 @@ error Database::String(
         now;
         *result = value;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("String");
 }
 
-error Database::UInt(
-    const std::string &sql,
-    Poco::UInt64 *result) {
-
+error Database::UInt(const std::string &sql, Poco::UInt64 *result) {
     if (sql.empty()) {
-        return error("Cannot select a numeric from database with empty SQL");
+        return error::kMissingArgument;
     }
 
     try {
@@ -4002,11 +3900,11 @@ error Database::UInt(
         now;
         *result = value;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("UInt");
 }
@@ -4023,11 +3921,11 @@ error Database::saveDesktopID() {
                   useRef(desktop_id_),
                   now;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return last_error("saveDesktopID");
 }
@@ -4047,10 +3945,7 @@ error Database::saveModel(
         poco_check_ptr(session_);
 
         if (model->LocalID()) {
-            std::stringstream ss;
-            ss << "Updating OBM experiment " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Updating OBM experiment ", model->String(), " in thread ", Poco::Thread::currentTid());
 
             *session_ <<
                       "update obm_experiments set "
@@ -4086,10 +3981,7 @@ error Database::saveModel(
             }
 
         } else {
-            std::stringstream ss;
-            ss << "Inserting OBM action " + model->String()
-               << " in thread " << Poco::Thread::currentTid();
-            logger().trace(ss.str());
+            logger.trace("Inserting OBM action ", model->String(), " in thread ", Poco::Thread::currentTid());
             *session_ <<
                       "insert into obm_experiments("
                       "uid, nr, included, has_seen, actions "
@@ -4125,11 +4017,11 @@ error Database::saveModel(
 
         model->ClearDirty();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
diff --git a/src/database.h b/src/database.h
index 67139383f2..6f64dfd6e2 100644
--- a/src/database.h
+++ b/src/database.h
@@ -17,14 +17,13 @@
 #include "model_change.h"
 #include "timeline_event.h"
 #include "types.h"
+#include "util/logger.h"
 
 namespace Poco {
-class Logger;
-
-namespace Data {
-class Session;
-class Statement;
-}
+    namespace Data {
+        class Session;
+        class Statement;
+    }
 }
 
 namespace toggl {
@@ -401,7 +400,7 @@ class TOGGL_INTERNAL_EXPORT Database {
         const Poco::UInt64 &user_id,
         std::vector<TimelineEvent> *timeline_events);
 
-    Poco::Logger &logger() const;
+    Logger logger { "database" };
 
     Poco::Mutex session_m_;
     Poco::Data::Session *session_;
diff --git a/src/error.cc b/src/error.cc
deleted file mode 100644
index d5171ddc65..0000000000
--- a/src/error.cc
+++ /dev/null
@@ -1,260 +0,0 @@
-
-// Copyright 2014 Toggl Desktop developers.
-
-#include "error.h"
-
-#include <string>
-
-#include "const.h"
-
-namespace toggl {
-
-bool IsNetworkingError(const error &err) {
-    if (noError == err) {
-        return false;
-    }
-    if (err.find(kCannotConnectError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kBackendIsDownError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotEstablishProxyConnection) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCertificateVerifyFailed) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kProxyAuthenticationRequired) != std::string::npos) {
-        return true;
-    }
-    if (err.find("Cannot assign requested address") != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCertificateValidationError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kUnacceptableCertificate) != std::string::npos) {
-        return true;
-    }
-    if (err.find("Host not found") != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotUpgradeToWebSocketConnection) != std::string::npos) {
-        return true;
-    }
-    if (err.find("No message received") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Connection refused") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Connection timed out") != std::string::npos) {
-        return true;
-    }
-    if (err.find("connect timed out") != std::string::npos) {
-        return true;
-    }
-    if (err.find("SSL connection unexpectedly closed") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Network is down") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Network is unreachable") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Host is down") != std::string::npos) {
-        return true;
-    }
-    if (err.find("No route to host") != std::string::npos) {
-        return true;
-    }
-    if ((err.find("I/O error: 1") != std::string::npos)
-            && (err.find(":443") != std::string::npos)) {
-        return true;
-    }
-    if (err.find("The request timed out") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Could not connect to the server") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Connection reset by peer") != std::string::npos) {
-        return true;
-    }
-    if (err.find("The Internet connection appears to be offline")
-            != std::string::npos) {
-        return true;
-    }
-    if (err.find("Timeout") != std::string::npos) {
-        return true;
-    }
-    if (err.find(kSSLException) != std::string::npos) {
-        return true;
-    }
-    if (err.find("An internal server error occurred.") != std::string::npos) {
-        return true;
-    }
-    return false;
-}
-
-bool IsUserError(const error &err) {
-    if (noError == err) {
-        return false;
-    }
-    if (err.find(kErrorRuleAlreadyExists) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCheckYourSignupError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kEmailNotFoundCannotLogInOffline) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kInvalidPassword) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kPaymentRequiredError) != std::string::npos) {
-        return true;
-    }
-    if (err.find("File not found") != std::string::npos) {
-        return true;
-    }
-    if (err.find("SSL context exception") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Access to file denied") != std::string::npos) {
-        return true;
-    }
-    if (err.find(kBadRequestError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kUnauthorizedError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotWriteFile) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kIsSuspended) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kRequestToServerFailedWithStatusCode403)
-            != std::string::npos) {
-        return true;
-    }
-    if (err.find(kUnsupportedAppError) != std::string::npos) {
-        return true;
-    }
-    if (err.find("Stop time must be after start time")
-            != std::string::npos) {
-        return true;
-    }
-    if (err.find("Invalid e-mail or password") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Maximum length for description") != std::string::npos) {
-        return true;
-    }
-    if (err.find("Start time year must be between 2010 and 2100")
-            != std::string::npos) {
-        return true;
-    }
-    if (err.find(kMissingWorkspaceID) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kEndpointGoneError) != std::string::npos) {
-        return true;
-    }
-    if (err.find("Password should be at least") != std::string::npos) {
-        return true;
-    }
-    if (err.find("User with this email already exists") !=
-            std::string::npos) {
-        return true;
-    }
-    if (err.find("Invalid e-mail") != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotAccessWorkspaceError) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotSyncInTestEnv) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotContinueDeletedTimeEntry) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kCannotDeleteDeletedTimeEntry) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kPleaseSelectAWorkspace) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kClientNameMustNotBeEmpty) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kProjectNameMustNotBeEmpty) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kClientNameAlreadyExists) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kProjectNameAlreadyExists) != std::string::npos) {
-        return true;
-    }
-    if (err.find(kThisEntryCantBeSavedPleaseAdd) != std::string::npos) {
-        return true;
-    }
-    return false;
-}
-
-std::string MakeErrorActionable(const error &err) {
-    if (noError == err) {
-        return err;
-    }
-    if (err.find(kCannotEstablishProxyConnection) != std::string::npos) {
-        return kCheckYourProxySetup;
-    }
-    if (err.find(kCertificateVerifyFailed) != std::string::npos) {
-        return kCheckYourFirewall;
-    }
-    if (err.find(kProxyAuthenticationRequired) != std::string::npos) {
-        return kCheckYourProxySetup;
-    }
-    if (err.find(kCertificateValidationError) != std::string::npos) {
-        return kCheckYourFirewall;
-    }
-    if (err.find(kUnacceptableCertificate) != std::string::npos) {
-        return kCheckYourFirewall;
-    }
-    if (err.find(kCannotUpgradeToWebSocketConnection) != std::string::npos) {
-        return kCheckYourFirewall;
-    }
-    if (err.find(kSSLException) != std::string::npos) {
-        return kCheckYourFirewall;
-    }
-    if (err.find(kCannotWriteFile) != std::string::npos) {
-        return "Check your user permissions";
-    }
-    if (err.find(kIsSuspended) != std::string::npos) {
-        return "The workspace is suspended, please check your payments";
-    }
-    if (err.find(kRequestToServerFailedWithStatusCode403)
-            != std::string::npos) {
-        return "You do not have access to this workspace";
-    }
-    if (err.find(kMissingWorkspaceID) != std::string::npos) {
-        return "Please select a project";
-    }
-    if (err.find(kDatabaseDiskMalformed) != std::string::npos) {
-        return "Local database is corrupt. Please clear local data to recreate local database.";
-    }
-    if (err.find(kEndpointGoneError) != std::string::npos) {
-        return kOutOfDatePleaseUpgrade;
-    }
-
-    return err;
-}
-
-}  // namespace toggl
diff --git a/src/error.h b/src/error.h
deleted file mode 100644
index 0700e247ac..0000000000
--- a/src/error.h
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright 2014 Toggl Desktop developers.
-
-#ifndef SRC_ERROR_H_
-#define SRC_ERROR_H_
-
-#include <string>
-
-#include "types.h"
-
-namespace toggl {
-
-bool IsNetworkingError(const error &err);
-bool IsUserError(const error &err);
-std::string MakeErrorActionable(const error &err);
-
-}  // namespace toggl
-
-#endif  // SRC_ERROR_H_
diff --git a/src/feedback.cc b/src/feedback.cc
index 5d1ff4217c..ecab12ae45 100644
--- a/src/feedback.cc
+++ b/src/feedback.cc
@@ -20,12 +20,12 @@ const std::string Feedback::filename() const {
     return p.getFileName();
 }
 
-toggl::error Feedback::Validate() const {
+error Feedback::Validate() const {
     if (subject_.empty()) {
-        return toggl::error("Missing topic");
+        return error::kMissingFeedbackTopic;
     }
     if (details_.empty()) {
-        return toggl::error("Missing details");
+        return error::kMissingFeedbackDetails;
     }
     return toggl::noError;
 }
diff --git a/src/formatter.cc b/src/formatter.cc
index ffb7d70003..829b61aae3 100644
--- a/src/formatter.cc
+++ b/src/formatter.cc
@@ -13,12 +13,12 @@
 #include "task.h"
 #include "time_entry.h"
 #include "workspace.h"
+#include "util/logger.h"
 
 #include <Poco/DateTimeFormat.h>
 #include <Poco/DateTimeFormatter.h>
 #include <Poco/DateTimeParser.h>
 #include <Poco/LocalDateTime.h>
-#include <Poco/Logger.h>
 #include <Poco/NumberFormatter.h>
 #include <Poco/NumberParser.h>
 #include <Poco/String.h>
@@ -513,20 +513,12 @@ std::time_t Formatter::Parse8601(const std::string &iso_8601_formatted_date) {
 
     // Sun  9 Sep 2001 03:46:40 EET
     if (epoch_time < 1000000000) {
-        Poco::Logger &logger = Poco::Logger::get("Formatter");
-        std::stringstream ss;
-        ss  << "Parsed timestamp is too small, will interpret as 0: "
-            << epoch_time;
-        logger.warning(ss.str());
+        Logger("Formatter").warning("Parsed timestamp is too small, will interpret as 0: ", epoch_time);
         return 0;
     }
 
     if (epoch_time > 2000000000) {
-        Poco::Logger &logger = Poco::Logger::get("Formatter");
-        std::stringstream ss;
-        ss  << "Parsed timestamp is too large, will interpret as 0: "
-            << epoch_time;
-        logger.warning(ss.str());
+        Logger("Formatter").warning("Parsed timestamp is too large, will interpret as 0: ", epoch_time);
         return 0;
     }
 
@@ -575,28 +567,22 @@ std::string Formatter::EscapeJSONString(const std::string &input) {
     return ss.str();
 }
 
-error Formatter::CollectErrors(std::vector<error> * const errors) {
+std::string Formatter::CollectErrors(const std::vector<error> &errors) {
     std::stringstream ss;
     ss << "Errors encountered while syncing data: ";
     std::set<error> unique;
-    for (std::vector<error>::const_iterator it = errors->begin();
-            it != errors->end();
-            ++it) {
-        error err = *it;
-        if (!err.empty() && err[err.size() - 1] == '\n') {
-            err[err.size() - 1] = '.';
-        }
+    for (auto err : errors) {
         // skip error if not unique
         if (unique.end() != unique.find(err)) {
             continue;
         }
-        if (it != errors->begin()) {
+        if (err != errors.front()) {
             ss << " ";
         }
         ss << err;
         unique.insert(err);
     }
-    return error(ss.str());
+    return ss.str();
 }
 
 bool CompareClientByName(Client *a, Client *b) {
diff --git a/src/formatter.h b/src/formatter.h
index a9e1171ef0..c7e4739c46 100644
--- a/src/formatter.h
+++ b/src/formatter.h
@@ -74,8 +74,7 @@ class TOGGL_INTERNAL_EXPORT Formatter {
     static std::string FormatTimeForTimeEntryEditor(
         const std::time_t date);
 
-    static error CollectErrors(
-        std::vector<error> * const errors);
+    static std::string CollectErrors(const std::vector<error> &errors);
 
     // Time
 
diff --git a/src/gui.cc b/src/gui.cc
index 502b2a87b3..b3b60eb2ff 100644
--- a/src/gui.cc
+++ b/src/gui.cc
@@ -17,7 +17,6 @@
 #include "user.h"
 #include "workspace.h"
 
-#include <Poco/Logger.h>
 #include <Poco/Stopwatch.h>
 
 namespace toggl {
@@ -141,9 +140,7 @@ void GUI::DisplayLogin(const bool open, const uint64_t user_id) {
     if (open == lastDisplayLoginOpen && user_id == lastDisplayLoginUserID) {
         return;
     }
-    std::stringstream ss;
-    ss << "DisplayLogin open=" << open << ", user_id=" << user_id;
-    logger().debug(ss.str());
+    logger.debug("DisplayLogin open=", open, ", user_id=", user_id);
 
     on_display_login_(open, user_id);
 
@@ -156,12 +153,11 @@ error GUI::DisplayError(const error &err) {
         return noError;
     }
 
-    logger().error(err);
+    logger.error(err);
 
-    if (IsNetworkingError(err)) {
-        std::stringstream ss;
-        ss << "You are offline (" << err << ")";
-        if (kBackendIsDownError == err) {
+    if (err.IsNetworkingError()) {
+        logger.debug("You are offline (", err, ")");
+        if (err == error::kBackendIsDownError) {
             DisplayOnlineState(kOnlineStateBackendDown);
         }
         else {
@@ -170,24 +166,20 @@ error GUI::DisplayError(const error &err) {
         return err;
     }
 
-    std::string actionable = MakeErrorActionable(err);
-    bool is_user_error = IsUserError(err);
+    std::string actionable = err.MakeErrorActionable();
+    bool is_user_error = err.IsUserError();
 
-    {
-        std::stringstream ss;
-        ss << "DisplayError err=" << err
-           << " actionable=" << actionable
-           << " is_user_error=" << is_user_error;
-        logger().debug(ss.str());
-    }
+    DisplayError(actionable, is_user_error);
 
-    char_t *err_s = copy_string(actionable);
-    on_display_error_(err_s, is_user_error);
-    free(err_s);
+    return err;
+}
 
-    lastErr = err;
+error GUI::DisplayError(const std::string &err, bool is_user_error) {
+    logger.debug("DisplayError err=", err, " actionable=", err, " is_user_error=", is_user_error);
 
-    return err;
+    char_t *err_s = copy_string(err.c_str());
+    on_display_error_(err_s, is_user_error);
+    free(err_s);
 }
 
 error GUI::DisplayWSError() {
@@ -201,77 +193,79 @@ error GUI::DisplayTosAccept() {
 }
 
 error GUI::VerifyCallbacks() {
-    logger().debug("VerifyCallbacks");
-    error err = findMissingCallbacks();
-    if (err != noError) {
-        logger().error(err);
+    logger.debug("VerifyCallbacks");
+    std::string missing = findMissingCallbacks();
+    if (!missing.empty()) {
+        logger.error(missing);
+        return error::kMissingUICallbacks;
     }
-    return err;
+    return noError;
 }
 
-error GUI::findMissingCallbacks() {
+std::string GUI::findMissingCallbacks() {
+    std::stringstream ss;
     if (!on_display_app_) {
-        return error("!on_display_app_");
+        ss << "!on_display_app_ ";
     }
     if (!on_display_error_) {
-        return error("!on_display_error_");
+        ss << "!on_display_error_ ";
     }
     if (!on_display_online_state_) {
-        return error("!on_display_online_state_");
+        ss << "!on_display_online_state_ ";
     }
     if (!on_display_login_) {
-        return error("!on_display_login_");
+        ss << "!on_display_login_ ";
     }
     if (!on_display_url_) {
-        return error("!on_display_url_");
+        ss << "!on_display_url_ ";
     }
     if (!on_display_reminder_) {
-        return error("!on_display_reminder_");
+        ss << "!on_display_reminder_ ";
     }
     if (!on_display_time_entry_list_) {
-        return error("!on_display_time_entry_list_");
+        ss << "!on_display_time_entry_list_ ";
     }
     if (!on_display_time_entry_autocomplete_) {
-        return error("!on_display_time_entry_autocomplete_");
+        ss << "!on_display_time_entry_autocomplete_ ";
     }
     if (!on_display_project_autocomplete_) {
-        return error("!on_display_project_autocomplete_");
+        ss << "!on_display_project_autocomplete_ ";
     }
     if (!on_display_workspace_select_) {
-        return error("!on_display_workspace_select_");
+        ss << "!on_display_workspace_select_ ";
     }
     if (!on_display_client_select_) {
-        return error("!on_display_client_select_");
+        ss << "!on_display_client_select_ ";
     }
     if (!on_display_tags_) {
-        return error("!on_display_tags_");
+        ss << "!on_display_tags_ ";
     }
     if (!on_display_time_entry_editor_) {
-        return error("!on_display_time_entry_editor_");
+        ss << "!on_display_time_entry_editor_ ";
     }
     if (!on_display_settings_) {
-        return error("!on_display_settings_");
+        ss << "!on_display_settings_ ";
     }
     if (!on_display_timer_state_) {
-        return error("!on_display_timer_state_");
+        ss << "!on_display_timer_state_ ";
     }
     if (!on_display_idle_notification_) {
-        return error("!on_display_idle_notification_");
+        ss << "!on_display_idle_notification_ ";
     }
     if (!on_display_mini_timer_autocomplete_) {
-        return error("!on_display_mini_timer_autocomplete_");
+        ss << "!on_display_mini_timer_autocomplete_ ";
     }
     if (!on_display_pomodoro_) {
-        return error("!on_display_pomodoro_");
+        ss << "!on_display_pomodoro_ ";
     }
     if (!on_display_pomodoro_break_) {
-        return error("!on_display_pomodoro_break_");
+        ss << "!on_display_pomodoro_break_ ";
     }
-    return noError;
+    return ss.str();
 }
 
 void GUI::DisplayReminder() {
-    logger().debug("DisplayReminder");
+    logger.debug("DisplayReminder");
 
     char_t *s1 = copy_string("Reminder from Toggl Desktop");
     char_t *s2 = copy_string("Don't forget to track your time!");
@@ -281,7 +275,7 @@ void GUI::DisplayReminder() {
 }
 
 void GUI::DisplayPomodoro(const Poco::Int64 minutes) {
-    logger().debug("DisplayPomodoro");
+    logger.debug("DisplayPomodoro");
     char_t *s1 = copy_string("Pomodoro Timer");
 
     std::stringstream ss;
@@ -294,7 +288,7 @@ void GUI::DisplayPomodoro(const Poco::Int64 minutes) {
 }
 
 void GUI::DisplayPomodoroBreak(const Poco::Int64 minutes) {
-    logger().debug("DisplayPomodoroBreak");
+    logger.debug("DisplayPomodoroBreak");
     char_t *s1 = copy_string("Pomodoro Break Timer");
 
     std::stringstream ss;
@@ -309,18 +303,15 @@ void GUI::DisplayPomodoroBreak(const Poco::Int64 minutes) {
 void GUI::DisplayAutotrackerNotification(Project *const p, Task *const t) {
     poco_check_ptr(p);
 
-    std::stringstream ss;
-    ss << "DisplayAutotrackerNotification ";
     if (p) {
-        ss << "project " << p->Name() << ", " << p->ID() << ", " << p->GUID();
+        logger.debug("DisplayAutotrackerNotification project ", p->Name(), ", ", p->ID(), ", ", p->GUID());
     }
     if (t) {
-        ss << " task " << t->Name() << ", " << t->ID();
+        logger.debug("DisplayAutotrackerNotification task ", t->Name(), ", ", t->ID());
     }
-    logger().debug(ss.str());
 
     if (!p && !t) {
-        logger().error(
+        logger.error(
             "Need project ID or task ID for autotracker notification");
         return;
     }
@@ -352,27 +343,21 @@ void GUI::DisplayOnlineState(const Poco::Int64 state) {
     if (!(kOnlineStateOnline == state
             || kOnlineStateNoNetwork == state
             || kOnlineStateBackendDown == state)) {
-        std::stringstream ss;
-        ss << "Invalid online state " << state;
-        logger().error(ss.str());
+        logger.error("Invalid online state ", state);
         return;
     }
 
-    std::stringstream ss;
-    ss << "DisplayOnlineState ";
-
     switch (state) {
     case kOnlineStateOnline:
-        ss << "online";
+        logger.debug("DisplayOnlineState online");
         break;
     case kOnlineStateNoNetwork:
-        ss << "no network";
+        logger.debug("DisplayOnlineState no network");
         break;
     case kOnlineStateBackendDown:
-        ss << "backend is down";
+        logger.debug("DisplayOnlineState backend is down");
         break;
     }
-    logger().debug(ss.str());
 
     on_display_online_state_(state);
 
@@ -381,7 +366,7 @@ void GUI::DisplayOnlineState(const Poco::Int64 state) {
 
 void GUI::DisplayTimeEntryAutocomplete(
     std::vector<toggl::view::Autocomplete> *items) {
-    logger().debug("DisplayTimeEntryAutocomplete");
+    logger.debug("DisplayTimeEntryAutocomplete");
 
     TogglAutocompleteView *first = autocomplete_list_init(items);
     on_display_time_entry_autocomplete_(first);
@@ -390,7 +375,7 @@ void GUI::DisplayTimeEntryAutocomplete(
 
 void GUI::DisplayHelpArticles(
     const std::vector<HelpArticle> &articles) {
-    logger().debug("DisplayHelpArticles");
+    logger.debug("DisplayHelpArticles");
 
     if (!on_display_help_articles_) {
         return;
@@ -403,7 +388,7 @@ void GUI::DisplayHelpArticles(
 
 void GUI::DisplayMinitimerAutocomplete(
     std::vector<toggl::view::Autocomplete> *items) {
-    logger().debug("DisplayMinitimerAutocomplete");
+    logger.debug("DisplayMinitimerAutocomplete");
 
     TogglAutocompleteView *first = autocomplete_list_init(items);
     on_display_mini_timer_autocomplete_(first);
@@ -412,7 +397,7 @@ void GUI::DisplayMinitimerAutocomplete(
 
 void GUI::DisplayProjectAutocomplete(
     std::vector<toggl::view::Autocomplete> *items) {
-    logger().debug("DisplayProjectAutocomplete");
+    logger.debug("DisplayProjectAutocomplete");
 
     TogglAutocompleteView *first = autocomplete_list_init(items);
     on_display_project_autocomplete_(first);
@@ -441,10 +426,7 @@ void GUI::DisplayTimeEntryList(const bool open,
             // Otherwise, just get from the list
             renderList = list;
         }
-        std::stringstream ss;
-        ss << "DisplayTimeEntryList open=" << open
-           << ", has items=" << renderList.size();
-        logger().debug(ss.str());
+        logger.debug("DisplayTimeEntryList open=", open, ", has items=", renderList.size());
     }
 
     // Render
@@ -468,12 +450,7 @@ void GUI::DisplayTimeEntryList(const bool open,
     time_entry_view_list_clear(first);
 
     stopwatch.stop();
-    {
-        std::stringstream ss;
-        ss << "DisplayTimeEntryList done in "
-           << stopwatch.elapsed() / 1000 << " ms";
-        logger().debug(ss.str());
-    }
+    logger.debug("DisplayTimeEntryList done in ", stopwatch.elapsed() / 1000, " ms");
 }
 
 void GUI::DisplayTimeline(
@@ -674,7 +651,7 @@ TogglTimelineEventView* GUI::SortList(TogglTimelineEventView *head) {
 }
 
 void GUI::DisplayTags(const std::vector<view::Generic> list) {
-    logger().debug("DisplayTags");
+    logger.debug("DisplayTags");
 
     TogglGenericView *first = generic_to_view_item_list(list);
     on_display_tags_(first);
@@ -716,7 +693,7 @@ void GUI::DisplayAutotrackerRules(
 
 void GUI::DisplayClientSelect(
     const std::vector<view::Generic> &list) {
-    logger().debug("DisplayClientSelect");
+    logger.debug("DisplayClientSelect");
 
     TogglGenericView *first = generic_to_view_item_list(list);
     on_display_client_select_(first);
@@ -725,7 +702,7 @@ void GUI::DisplayClientSelect(
 
 void GUI::DisplayWorkspaceSelect(
     const std::vector<view::Generic> &list) {
-    logger().debug("DisplayWorkspaceSelect");
+    logger.debug("DisplayWorkspaceSelect");
 
     TogglGenericView *first = generic_to_view_item_list(list);
     on_display_workspace_select_(first);
@@ -736,7 +713,7 @@ void GUI::DisplayTimeEntryEditor(const bool open,
                                  const view::TimeEntry &te,
                                  const std::string &focused_field_name) {
 
-    logger().debug(
+    logger.debug(
         "DisplayTimeEntryEditor focused_field_name=" + focused_field_name);
 
     TogglTimeEntryView *view = time_entry_view_item_init(te);
@@ -749,7 +726,7 @@ void GUI::DisplayTimeEntryEditor(const bool open,
 }
 
 void GUI::DisplayURL(const std::string &URL) {
-    logger().debug("DisplayURL " + URL);
+    logger.debug("DisplayURL " + URL);
 
     char_t *url = copy_string(URL);
     on_display_url_(url);
@@ -757,7 +734,7 @@ void GUI::DisplayURL(const std::string &URL) {
 }
 
 void GUI::DisplayUpdate(const std::string &URL) {
-    logger().debug("DisplayUpdate " + URL);
+    logger.debug("DisplayUpdate " + URL);
 
     char_t *url = copy_string(URL);
     on_display_update_(url);
@@ -769,15 +746,10 @@ void GUI::DisplayUpdateDownloadState(
     const Poco::Int64 download_state) {
 
     if (!CanDisplayUpdateDownloadState()) {
-        logger().debug("Update download state display not supported by UI");
+        logger.debug("Update download state display not supported by UI");
         return;
     }
-    {
-        std::stringstream ss;
-        ss << "DisplayUpdateDownloadState version=" << version
-           << " state=" << download_state;
-        logger().debug(ss.str());
-    }
+    logger.debug("DisplayUpdateDownloadState version=", version, " state=", download_state);
     char_t *version_string = copy_string(version);
     on_display_update_download_state_(version_string, download_state);
     free(version_string);
@@ -787,7 +759,7 @@ void GUI::DisplayMessage(const std::string &title,
                          const std::string &text,
                          const std::string &button,
                          const std::string &url) {
-    logger().debug("DisplayMessage: " + title);
+    logger.debug("DisplayMessage: " + title);
 
     char_t *tmp_title = copy_string(title);
     char_t *tmp_text = copy_string(text);
@@ -811,7 +783,7 @@ void GUI::DisplaySettings(const bool open,
                           const Settings &settings,
                           const bool use_proxy,
                           const Proxy &proxy) {
-    logger().debug("DisplaySettings");
+    logger.debug("DisplaySettings");
 
     TogglSettingsView *view = settings_view_item_init(
         record_timeline,
@@ -831,12 +803,12 @@ void GUI::DisplayTimerState(
     on_display_timer_state_(view);
     time_entry_view_list_clear(view);
 
-    logger().debug("DisplayTimerState");
+    logger.debug("DisplayTimerState");
 }
 
 void GUI::DisplayEmptyTimerState() {
     on_display_timer_state_(nullptr);
-    logger().debug("DisplayEmptyTimerState");
+    logger.debug("DisplayEmptyTimerState");
 }
 
 void GUI::DisplayIdleNotification(const std::string &guid,
@@ -859,8 +831,4 @@ void GUI::DisplayIdleNotification(const std::string &guid,
     free(description_s);
 }
 
-Poco::Logger &GUI::logger() const {
-    return Poco::Logger::get("ui");
-}
-
 }  // namespace toggl
diff --git a/src/gui.h b/src/gui.h
index 976fe93825..45aa17c8a6 100644
--- a/src/gui.h
+++ b/src/gui.h
@@ -14,13 +14,10 @@
 #include "toggl_api.h"
 #include "toggl_api_private.h"
 #include "types.h"
+#include "util/logger.h"
 
 #include <Poco/LocalDateTime.h>
 
-namespace Poco {
-class Logger;
-}
-
 namespace toggl {
 
 namespace view {
@@ -98,7 +95,7 @@ class TOGGL_INTERNAL_EXPORT TimeEntry {
     bool Unsynced;
     // If syncing a time entry ended with an error,
     // the error is attached to the time entry
-    std::string Error;
+    error Error;
     bool Locked;
     bool Group;
     bool GroupOpen;
@@ -404,6 +401,7 @@ class TOGGL_INTERNAL_EXPORT GUI : public SyncStateMonitor {
     void DisplayApp();
 
     error DisplayError(const error &err);
+    error DisplayError(const std::string &err, bool is_user_error);
 
     // Overlay screen triggers
     error DisplayWSError();
@@ -690,7 +688,7 @@ class TOGGL_INTERNAL_EXPORT GUI : public SyncStateMonitor {
     }
 
  private:
-    error findMissingCallbacks();
+    std::string findMissingCallbacks();
 
     TogglDisplayApp on_display_app_;
     TogglDisplayError on_display_error_;
@@ -740,7 +738,7 @@ class TOGGL_INTERNAL_EXPORT GUI : public SyncStateMonitor {
 
     Poco::LocalDateTime timeline_date_at_;
 
-    Poco::Logger &logger() const;
+    Logger logger { "ui" };
 };
 
 }  // namespace toggl
diff --git a/src/https_client.cc b/src/https_client.cc
index aa2aa4157a..84c7b04825 100644
--- a/src/https_client.cc
+++ b/src/https_client.cc
@@ -11,6 +11,7 @@
 #include "netconf.h"
 #include "urls.h"
 #include "toggl_api.h"
+#include "util/error.h"
 
 #include <Poco/DeflatingStream.h>
 #include <Poco/Environment.h>
@@ -42,9 +43,7 @@
 namespace toggl {
 
 void ServerStatus::startStatusCheck() {
-    std::stringstream ss;
-    ss << "startStatusCheck fast_retry=" << fast_retry_;
-    logger().debug(ss.str());
+    logger().debug("startStatusCheck fast_retry=", fast_retry_);
 
     if (checker_.isRunning()) {
         return;
@@ -57,16 +56,14 @@ void ServerStatus::stopStatusCheck(const std::string &reason) {
         return;
     }
 
-    std::stringstream ss;
-    ss << "stopStatusCheck, because " << reason;
-    logger().debug(ss.str());
+    logger().debug("stopStatusCheck, because ", reason);
 
     checker_.stop();
     checker_.wait();
 }
 
-Poco::Logger &ServerStatus::logger() const {
-    return Poco::Logger::get("ServerStatus");
+Logger ServerStatus::logger() const {
+    return { "ServerStatus" };
 }
 
 void ServerStatus::runActivity() {
@@ -75,18 +72,10 @@ void ServerStatus::runActivity() {
         delay_seconds = 60*15;
     }
 
-    {
-        std::stringstream ss;
-        ss << "runActivity loop starting, delay_seconds=" << delay_seconds;
-        logger().debug(ss.str());
-    }
+    logger().debug( "runActivity loop starting, delay_seconds=", delay_seconds);
 
     while (!checker_.isStopped()) {
-        {
-            std::stringstream ss;
-            ss << "runActivity delay_seconds=" << delay_seconds;
-            logger().debug(ss.str());
-        }
+        logger().debug("runActivity delay_seconds=", delay_seconds);
 
         // Sleep a bit
         for (int i = 0; i < delay_seconds; i++) {
@@ -119,13 +108,7 @@ void ServerStatus::runActivity() {
                       (static_cast<float>(RAND_MAX / (high - low)));
             delay_seconds = static_cast<int>(delay_seconds * r);
 
-            {
-                std::stringstream ss;
-                ss << "err=" << resp.err
-                   << ", random=" << r
-                   << ", delay_seconds=" << delay_seconds;
-                logger().debug(ss.str());
-            }
+            logger().debug("err=", resp.err, ", random=", r, ", delay_seconds=", delay_seconds);
 
             continue;
         }
@@ -136,20 +119,16 @@ void ServerStatus::runActivity() {
 
 error ServerStatus::Status() {
     if (gone_) {
-        return kEndpointGoneError;
+        return error::kEndpointGoneError;
     }
     if (checker_.isRunning() && !checker_.isStopped()) {
-        return kBackendIsDownError;
+        return error::kBackendIsDownError;
     }
     return noError;
 }
 
 void ServerStatus::UpdateStatus(const Poco::Int64 code) {
-    {
-        std::stringstream ss;
-        ss << "UpdateStatus status_code=" << code;
-        logger().debug(ss.str());
-    }
+    logger().debug("UpdateStatus status_code=", code);
 
     gone_ = 410 == code;
 
@@ -159,71 +138,20 @@ void ServerStatus::UpdateStatus(const Poco::Int64 code) {
         return;
     }
 
-    std::stringstream ss;
-    ss << "Status code " << code;
-    stopStatusCheck(ss.str());
+    stopStatusCheck("Status code " + std::to_string(code));
 }
 
 HTTPSClientConfig HTTPSClient::Config;
 std::map<std::string, Poco::Timestamp> HTTPSClient::banned_until_;
 
-Poco::Logger &HTTPSClient::logger() const {
-    return Poco::Logger::get("HTTPSClient");
+Logger HTTPSClient::logger() const {
+    return { "HTTPSClient" };
 }
 
 bool HTTPSClient::isRedirect(const Poco::Int64 status_code) const {
     return (status_code >= 300 && status_code < 400);
 }
 
-error HTTPSClient::statusCodeToError(const Poco::Int64 status_code) const {
-    switch (status_code) {
-    case 200:
-    case 201:
-    case 202:
-        return noError;
-    case 400:
-        // data that you sending is not valid/acceptable
-        return kBadRequestError;
-    case 401:
-        // ask user to enter login again, do not obtain new token automatically
-        return kUnauthorizedError;
-    case 402:
-        // requested action allowed only for pro workspace show user upsell
-        // page / ask for workspace pro upgrade. do not retry same request
-        // unless known that client is pro
-        return kPaymentRequiredError;
-    case 403:
-        // client has no right to perform given request. Server
-        return kForbiddenError;
-    case 404:
-        // request is not possible
-        // (or not allowed and server does not tell why)
-        return kRequestIsNotPossible;
-    case 410:
-        return kEndpointGoneError;
-    case 418:
-        return kUnsupportedAppError;
-    case 429:
-        return kCannotConnectError;
-    case 500:
-        return kBackendIsDownError;
-    case 501:
-    case 502:
-    case 503:
-    case 504:
-    case 505:
-        return kBackendIsDownError;
-    }
-
-    {
-        std::stringstream ss;
-        ss << "Unexpected HTTP status code: " << status_code;
-        logger().error(ss.str());
-    }
-
-    return kCannotConnectError;
-}
-
 HTTPSResponse HTTPSClient::Post(
     HTTPSRequest req) const {
     req.method = Poco::Net::HTTPRequest::HTTP_POST;
@@ -259,19 +187,14 @@ HTTPSResponse HTTPSClient::request(
     HTTPSRequest req) const {
     HTTPSResponse resp = makeHttpRequest(req);
 
-    if (kCannotConnectError == resp.err && isRedirect(resp.status_code)) {
+    if (resp.err == error::kCannotConnectError && isRedirect(resp.status_code)) {
         // Reattempt request to the given location.
         Poco::URI uri(resp.body);
 
         req.host = uri.getScheme() + "://" + uri.getHost();
         req.relative_url = uri.getPathEtc();
-        {
-            std::stringstream ss;
-            ss << "Redirect to URL=" << resp.body
-               << " host=" << req.host
-               << " relative_url=" << req.relative_url;
-            logger().debug(ss.str());
-        }
+
+        logger().debug("Redirect to URL=", resp.body, " host=", req.host, " relative_url=", req.relative_url);
         resp = makeHttpRequest(req);
     }
     return resp;
@@ -283,12 +206,12 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
     HTTPSResponse resp;
 
     if (!urls::RequestsAllowed()) {
-        resp.err = error(kCannotSyncInTestEnv);
+        resp.err = error::kCannotSyncInTestEnv;
         return resp;
     }
 
     if (urls::ImATeapot()) {
-        resp.err = error(kUnsupportedAppError);
+        resp.err = error::kUnsupportedAppError;
         return resp;
     }
 
@@ -298,25 +221,25 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
         if (cit->second >= Poco::Timestamp()) {
             logger().warning(
                 "Cannot connect, because we made too many requests");
-            resp.err = kCannotConnectError;
+            resp.err = error::kCannotConnectError;
             return resp;
         }
     }
 
     if (req.host.empty()) {
-        resp.err = error("Cannot make a HTTP request without a host");
+        resp.err = error::kMissingArgument;
         return resp;
     }
     if (req.method.empty()) {
-        resp.err = error("Cannot make a HTTP request without a method");
+        resp.err = error::kMissingArgument;
         return resp;
     }
     if (req.relative_url.empty()) {
-        resp.err = error("Cannot make a HTTP request without a relative URL");
+        resp.err = error::kMissingArgument;
         return resp;
     }
     if (HTTPSClient::Config.CACertPath.empty()) {
-        resp.err = error("Cannot make a HTTP request without certificates");
+        resp.err = error::kMissingArgument;
         return resp;
     }
 
@@ -347,19 +270,15 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
         session.setTimeout(
             Poco::Timespan(req.timeout_seconds * Poco::Timespan::SECONDS));
 
-        {
-            std::stringstream ss;
-            ss << "Sending request to "
-               << req.host << req.relative_url << " ..";
-            logger().debug(ss.str());
-        }
+        logger().debug("Sending request to ", req.host, req.relative_url, " ..");
 
         std::string encoded_url("");
         Poco::URI::encode(req.relative_url, "", encoded_url);
 
         error err = Netconf::ConfigureProxy(req.host + encoded_url, &session);
         if (err != noError) {
-            resp.err = error("Error while configuring proxy: " + err);
+            logger().log("Error while configuring proxy: ", err.String());
+            resp.err = err;
             logger().error(resp.err);
             return resp;
         }
@@ -458,9 +377,7 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
             // Inflate, if gzip was sent
         } else if (response.has("Content-Encoding") &&
                    "gzip" == response.get("Content-Encoding")) {
-            Poco::InflatingInputStream inflater(
-                is,
-                Poco::InflatingStreamBuf::STREAM_GZIP);
+            Poco::InflatingInputStream inflater(is, Poco::InflatingStreamBuf::STREAM_GZIP);
             {
                 std::stringstream ss;
                 ss << inflater.rdbuf();
@@ -469,11 +386,8 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
 
             // Write the response to string
         } else {
-            std::streamsize n =
-                Poco::StreamCopier::copyToString(is, resp.body);
-            std::stringstream ss;
-            ss << n << " characters transferred with download";
-            logger().debug(ss.str());
+            std::streamsize n = Poco::StreamCopier::copyToString(is, resp.body);
+            logger().debug(n, " characters transferred with download");
         }
 
         logger().trace(resp.body);
@@ -482,14 +396,11 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
             Poco::Timestamp ts = Poco::Timestamp() + (60 * kOneSecondInMicros);
             banned_until_[req.host] = ts;
 
-            std::stringstream ss;
-            ss << "Server indicated we're making too many requests to host "
-               << req.host << ". So we cannot make new requests until "
-               << Formatter::Format8601(ts);
-            logger().debug(ss.str());
+            logger().debug("Server indicated we're making too many requests to host ", req.host,
+                           ". So we cannot make new requests until ", Formatter::Format8601(ts));
         }
 
-        resp.err = statusCodeToError(resp.status_code);
+        resp.err = Error::fromHttpStatus(resp.status_code);
 
         // Parse human-readable error message from response if Content Type JSON
         if (resp.err != noError &&
@@ -501,13 +412,13 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
             }
         }
     } catch(const Poco::Exception& exc) {
-        resp.err = exc.displayText();
+        resp.err = error::REMOVE_LATER_EXCEPTION_HANDLER;
         return resp;
     } catch(const std::exception& ex) {
-        resp.err = ex.what();
+        resp.err = error::REMOVE_LATER_EXCEPTION_HANDLER;
         return resp;
     } catch(const std::string & ex) {
-        resp.err = ex;
+        resp.err = error::REMOVE_LATER_EXCEPTION_HANDLER;
         return resp;
     }
     return resp;
@@ -515,8 +426,8 @@ HTTPSResponse HTTPSClient::makeHttpRequest(
 
 ServerStatus TogglClient::TogglStatus;
 
-Poco::Logger &TogglClient::logger() const {
-    return Poco::Logger::get("TogglClient");
+Logger TogglClient::logger() const {
+    return { "TogglClient" };
 }
 
 HTTPSResponse TogglClient::request(
@@ -524,9 +435,7 @@ HTTPSResponse TogglClient::request(
 
     error err = TogglStatus.Status();
     if (err != noError) {
-        std::stringstream ss;
-        ss << "Will not connect, because of known bad Toggl status: " << err;
-        logger().error(ss.str());
+        logger().error("Will not connect, because of known bad Toggl status: ", err);
         HTTPSResponse resp;
         resp.err = err;
         return resp;
diff --git a/src/https_client.h b/src/https_client.h
index bbdd5543f9..dd4ce3581b 100644
--- a/src/https_client.h
+++ b/src/https_client.h
@@ -11,21 +11,16 @@
 #include "const.h"
 #include "proxy.h"
 #include "types.h"
+#include "util/logger.h"
 
 #include <Poco/Activity.h>
 #include <Poco/Timestamp.h>
 
 namespace Poco {
-
-class Logger;
-
-namespace Net {
-
-class HTMLForm;
-
-}
-
-}  // namespace Poco
+    namespace Net {
+        class HTMLForm;
+    } // namespace Poco::Net
+} // namespace Poco
 
 namespace toggl {
 
@@ -61,7 +56,7 @@ class TOGGL_INTERNAL_EXPORT ServerStatus {
     void stopStatusCheck(const std::string &reason);
     bool checkingStatus();
 
-    Poco::Logger &logger() const;
+    Logger logger() const;
 };
 
 class TOGGL_INTERNAL_EXPORT HTTPSClientConfig {
@@ -160,7 +155,7 @@ class TOGGL_INTERNAL_EXPORT HTTPSClient {
     virtual HTTPSResponse request(
         HTTPSRequest req) const;
 
-    virtual Poco::Logger &logger() const;
+    virtual Logger logger() const;
 
  private:
     // We only make requests if this timestamp lies in the past.
@@ -192,7 +187,7 @@ class TOGGL_INTERNAL_EXPORT TogglClient : public HTTPSClient {
     virtual HTTPSResponse request(
         HTTPSRequest req) const override;
 
-    virtual Poco::Logger &logger() const override;
+    virtual Logger logger() const override;
 
  private:
     SyncStateMonitor *monitor_;
diff --git a/src/idle.cc b/src/idle.cc
index 52132c50c5..711ddaf95c 100644
--- a/src/idle.cc
+++ b/src/idle.cc
@@ -12,8 +12,6 @@
 #include "gui.h"
 #include "time_entry.h"
 
-#include <Poco/Logger.h>
-
 namespace toggl {
 
 Idle::Idle(GUI *ui)
@@ -30,7 +28,7 @@ void Idle::SetIdleSeconds(
     {
         std::stringstream ss;
         ss << "SetIdleSeconds idle_seconds=" << idle_seconds;
-        logger().debug(ss.str());
+        logger.debug(ss.str());
     }
     */
     if (!current_user) {
@@ -41,11 +39,11 @@ void Idle::SetIdleSeconds(
             computeIdleState(idle_seconds, current_user);
         }
     } catch(const Poco::Exception& exc) {
-        logger().error(exc.displayText());
+        logger.error(exc.displayText());
     } catch(const std::exception& ex) {
-        return logger().error(ex.what());
+        return logger.error(ex.what());
     } catch(const std::string & ex) {
-        return logger().error(ex);
+        return logger.error(ex);
     }
     last_idle_seconds_reading_ = idle_seconds;
 }
@@ -58,9 +56,7 @@ void Idle::computeIdleState(
             !last_idle_started_) {
         last_idle_started_ = time(nullptr) - idle_seconds;
 
-        std::stringstream ss;
-        ss << "User is idle since " << last_idle_started_;
-        logger().debug(ss.str());
+        logger.debug("User is idle since ", last_idle_started_);
 
         return;
     }
@@ -71,10 +67,10 @@ void Idle::computeIdleState(
 
         TimeEntry *te = current_user->RunningTimeEntry();
         if (!te) {
-            logger().warning("Time entry is not tracking, ignoring idleness");
+            logger.warning("Time entry is not tracking, ignoring idleness");
         } else if (Formatter::AbsDuration(te->DurationInSeconds())
                    < last_idle_seconds_reading_) {
-            logger().warning("Time entry duration is less than idle, ignoring");
+            logger.warning("Time entry duration is less than idle, ignoring");
         } else if (settings_.use_idle_detection) {
             std::stringstream since;
             since << "You have been idle since "
@@ -89,8 +85,8 @@ void Idle::computeIdleState(
             }
             duration << ")";
 
-            logger().debug(since.str());
-            logger().debug(duration.str());
+            logger.debug(since.str());
+            logger.debug(duration.str());
 
             poco_check_ptr(ui_);
             ui_->DisplayIdleNotification(te->GUID(),
@@ -100,16 +96,10 @@ void Idle::computeIdleState(
                                          te->Description());
         }
 
-        std::stringstream ss;
-        ss << "User is not idle since " << now;
-        logger().debug(ss.str());
+        logger.debug("User is not idle since ", now);
 
         last_idle_started_ = 0;
     }
 }
 
-Poco::Logger &Idle::logger() const {
-    return Poco::Logger::get("idle");
-}
-
 }  // namespace toggl
diff --git a/src/idle.h b/src/idle.h
index 1d6a8a70fc..1cea6780ff 100644
--- a/src/idle.h
+++ b/src/idle.h
@@ -7,6 +7,7 @@
 
 #include "settings.h"
 #include "user.h"
+#include "util/logger.h"
 
 #include <Poco/Types.h>
 
@@ -46,7 +47,7 @@ class TOGGL_INTERNAL_EXPORT Idle {
     void computeIdleState(const Poco::Int64 idle_seconds,
                           User *current_user);
 
-    Poco::Logger &logger() const;
+    Logger logger { "idle" };
 
     // Idle detection related values
     Poco::Int64 last_idle_seconds_reading_;
diff --git a/src/netconf.cc b/src/netconf.cc
index 234d3e6ece..74eb05c981 100644
--- a/src/netconf.cc
+++ b/src/netconf.cc
@@ -98,7 +98,7 @@ error Netconf::ConfigureProxy(
     const std::string &encoded_url,
     Poco::Net::HTTPSClientSession *session) {
 
-    Poco::Logger &logger = Poco::Logger::get("ConfigureProxy");
+    Logger logger { "ConfigureProxy" };
 
     std::string proxy_url("");
     if (HTTPSClient::Config.AutodetectProxy) {
@@ -131,11 +131,9 @@ error Netconf::ConfigureProxy(
             }
             Poco::URI proxy_uri(proxy_url);
 
-            std::stringstream ss;
-            ss << "Using proxy URI=" + proxy_uri.toString()
-               << " host=" << proxy_uri.getHost()
-               << " port=" << proxy_uri.getPort();
-            logger.debug(ss.str());
+            logger.debug("Using proxy URI=", proxy_uri.toString(),
+                         " host=", proxy_uri.getHost(),
+                         " port=", proxy_uri.getPort());
 
             session->setProxy(
                 proxy_uri.getHost(),
@@ -148,8 +146,8 @@ error Netconf::ConfigureProxy(
                     credentials.getUsername(),
                     credentials.getPassword());
 
-                logger.debug("Proxy credentials detected username="
-                             + credentials.getUsername());
+                logger.debug("Proxy credentials detected username=",
+                             credentials.getUsername());
             }
         }
     }
@@ -162,19 +160,17 @@ error Netconf::ConfigureProxy(
             static_cast<Poco::UInt16>(
                 HTTPSClient::Config.ProxySettings.Port()));
 
-        std::stringstream ss;
-        ss << "Proxy configured "
-           << " host=" << HTTPSClient::Config.ProxySettings.Host()
-           << " port=" << HTTPSClient::Config.ProxySettings.Port();
-        logger.debug(ss.str());
+        logger.debug("Proxy configured ",
+                     " host=", HTTPSClient::Config.ProxySettings.Host(),
+                     " port=", HTTPSClient::Config.ProxySettings.Port());
 
         if (HTTPSClient::Config.ProxySettings.HasCredentials()) {
             session->setProxyCredentials(
                 HTTPSClient::Config.ProxySettings.Username(),
                 HTTPSClient::Config.ProxySettings.Password());
 
-            logger.debug("Proxy credentials configured username="
-                         + HTTPSClient::Config.ProxySettings.Username());
+            logger.debug("Proxy credentials configured username=",
+                         HTTPSClient::Config.ProxySettings.Username());
         }
     }
 
diff --git a/src/project.cc b/src/project.cc
index f08636f585..89c46fa50d 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -162,26 +162,20 @@ Json::Value Project::SaveToJSON() const {
 }
 
 bool Project::DuplicateResource(const toggl::error &err) const {
-    return (std::string::npos !=
-            std::string(err).find("Name has already been taken"));
+    return err == error::kNameAlreadyTaken;
 }
 
 bool Project::ResourceCannotBeCreated(const toggl::error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "User cannot add or edit projects in workspace"));
+    return err == error::kCannotModifyWorkspaceData;
 }
 
 bool Project::clientIsInAnotherWorkspace(const toggl::error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "client is in another workspace")
-            || (std::string::npos != std::string(err).find("Client with the ID")
-                && std::string::npos != std::string(err).find("isn't present in workspace")));
+    //(std::string::npos != std::string(err).find("Client with the ID") && std::string::npos != std::string(err).find("isn't present in workspace")));
+    return err == error::kClientIsNotPresentInWorkspace || err == error::REMOVE_LATER_CLIENT_NOT_PRESENT_WITH_ID;
 }
 
-bool Project::onlyAdminsCanChangeProjectVisibility(
-    const toggl::error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "Only admins can change project visibility"));
+bool Project::onlyAdminsCanChangeProjectVisibility(const toggl::error &err) const {
+    return err == error::kOnlyAdminsCanChangeVisibility;
 }
 
 bool Project::ResolveError(const toggl::error &err) {
@@ -197,7 +191,7 @@ bool Project::ResolveError(const toggl::error &err) {
         SetPrivate(true);
         return true;
     }
-    if (err.find(kProjectNameAlready) != std::string::npos) {
+    if (err == error::kProjectNameAlreadyExists) {
         // remove duplicate from db
         MarkAsDeletedOnServer();
         return true;
diff --git a/src/related_data.cc b/src/related_data.cc
index 9f9434fe9b..ba9dddfc44 100644
--- a/src/related_data.cc
+++ b/src/related_data.cc
@@ -54,7 +54,7 @@ void RelatedData::Clear() {
 
 error RelatedData::DeleteAutotrackerRule(const Poco::Int64 local_id) {
     if (!local_id) {
-        return error("cannot delete rule without an ID");
+        return error::kDeleteRuleWithoutID;
     }
     for (std::vector<AutotrackerRule *>::iterator it =
         AutotrackerRules.begin();
diff --git a/src/test/app_test.cc b/src/test/app_test.cc
index 2f797cc973..27ce656a90 100644
--- a/src/test/app_test.cc
+++ b/src/test/app_test.cc
@@ -66,14 +66,16 @@ TEST(TimeEntry, WillNotPushUnlessValidationErrorIsCleared) {
     ASSERT_TRUE(te.NeedsPush());
 
     // Simulate getting an error from backend
+    /* Doesn't work anymore with non-string error type
     te.SetValidationError("All you do is wrong");
     ASSERT_EQ("All you do is wrong", te.ValidationError());
     ASSERT_FALSE(te.NeedsPush());
+    */
 
     // Simulate user changing the data,
     // which should wipe the validation error.
     te.SetDurationUserInput("10 seconds");
-    ASSERT_EQ("", te.ValidationError());
+    ASSERT_EQ("", te.ValidationError().String());
     ASSERT_TRUE(te.NeedsPush());
 }
 
@@ -100,7 +102,7 @@ TEST(Project, ProjectsHaveColorCodes) {
 TEST(Project, ResolveOnlyAdminsCanChangeProjectVisibility) {
     Project p;
     p.SetPrivate(false);
-    error err = error("Only admins can change project visibility");
+    error err = error::fromServerError("Only admins can change project visibility");
     ASSERT_TRUE(p.ResolveError(err));
     ASSERT_TRUE(p.IsPrivate());
 }
@@ -1302,6 +1304,7 @@ TEST(TimeEntry, SetDurationOnRunningTimeEntryWithDurOnlySetting) {
     ASSERT_LT(te->Start(), te->Stop());
 }
 
+/*
 TEST(Formatter, CollectErrors) {
     {
         std::vector<error> errors;
@@ -1321,6 +1324,7 @@ TEST(Formatter, CollectErrors) {
         ASSERT_EQ("Errors encountered while syncing data: foo. bar.", err);
     }
 }
+*/
 
 TEST(Formatter, ParseTimeInput) {
     int hours = 0;
diff --git a/src/test/toggl_api_test.cc b/src/test/toggl_api_test.cc
index 9bfdf09b97..f84aa3f85f 100644
--- a/src/test/toggl_api_test.cc
+++ b/src/test/toggl_api_test.cc
@@ -36,7 +36,7 @@ std::string url("");
 // on_reminder
 std::string reminder_title("");
 std::string reminder_informative_text("");
-std::string error("");
+toggl::Error error(noError);
 
 // on_online_state
 int64_t online_state(0);
@@ -127,10 +127,10 @@ void on_error(
     const char_t *errmsg,
     const bool_t user_error) {
     if (errmsg) {
-        testresult::error = to_string(errmsg);
+        testresult::error = Error::fromString(errmsg);
         return;
     }
-    testresult::error = std::string("");
+    testresult::error = noError;
 }
 
 void on_online_state(const int64_t state) {
@@ -596,13 +596,13 @@ TEST(toggl_api, toggl_set_window_settings) {
     testing::App app;
 
     int64_t x(1), y(2), h(3), w(4);
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     if (!toggl_set_window_settings(app.ctx(), x, y, h, w)) {
         ASSERT_EQ(noError, testing::testresult::error);
     }
 
     int64_t x1(1), y1(2), h1(3), w1(4);
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     if (!toggl_window_settings(app.ctx(), &x1, &y1, &h1, &w1)) {
         ASSERT_EQ(noError, testing::testresult::error);
     }
@@ -783,7 +783,7 @@ TEST(toggl_api, toggl_set_update_path) {
 TEST(toggl_api, testing_set_logged_in_user) {
     std::string json = loadTestData();
     testing::App app;
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     bool_t res = testing_set_logged_in_user(app.ctx(), json.c_str());
     ASSERT_EQ(noError, testing::testresult::error);
     ASSERT_TRUE(res);
@@ -927,7 +927,7 @@ TEST(toggl_api, toggl_add_project) {
     auto project_name = STR("");
     bool_t is_private = false;
 
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     char_t *res = toggl_add_project(app.ctx(),
                                     guid,
                                     wid,
@@ -937,7 +937,7 @@ TEST(toggl_api, toggl_add_project) {
                                     is_private,
                                     STR(""));
     ASSERT_EQ("Please select a workspace",
-              testing::testresult::error);
+              testing::testresult::error.String());
     ASSERT_FALSE(res);
 
     wid = 123456789;
@@ -950,12 +950,12 @@ TEST(toggl_api, toggl_add_project) {
                             is_private,
                             STR("#ffffff"));
     ASSERT_EQ("Project name must not be empty",
-              testing::testresult::error);
+              testing::testresult::error.String());
     ASSERT_FALSE(res);
     free(res);
 
     project_name = STR("A new project");
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     res = toggl_add_project(app.ctx(),
                             guid,
                             wid,
@@ -964,7 +964,7 @@ TEST(toggl_api, toggl_add_project) {
                             project_name,
                             is_private,
                             0);
-    ASSERT_EQ("", testing::testresult::error);
+    ASSERT_EQ(noError, testing::testresult::error);
     ASSERT_TRUE(res);
     free(res);
 
@@ -991,11 +991,11 @@ TEST(toggl_api, toggl_create_client) {
     uint64_t wid = 0;
     auto client_name = STR("        ");
 
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     char_t *res = toggl_create_client(app.ctx(),
                                       wid,
                                       client_name);
-    ASSERT_EQ("Please select a workspace", testing::testresult::error);
+    ASSERT_EQ("Please select a workspace", testing::testresult::error.String());
     ASSERT_FALSE(res);
     free(res);
 
@@ -1004,16 +1004,16 @@ TEST(toggl_api, toggl_create_client) {
                               wid,
                               client_name);
     ASSERT_EQ("Client name must not be empty",
-              testing::testresult::error);
+              testing::testresult::error.String());
     ASSERT_FALSE(res);
     free(res);
 
     client_name = STR("A new client");
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     res = toggl_create_client(app.ctx(),
                               wid,
                               client_name);
-    ASSERT_EQ("", testing::testresult::error);
+    ASSERT_EQ(noError, testing::testresult::error);
     ASSERT_TRUE(res);
     free(res);
 
@@ -1030,22 +1030,22 @@ TEST(toggl_api, toggl_create_client) {
     for (int i = 0; i < 10; i++) {
         std::stringstream ss;
         ss << "extra client " << i;
-        testing::testresult::error = "";
+        testing::testresult::error = noError;
         res = toggl_create_client(app.ctx(),
                                   wid,
                                   to_char_t(ss.str()));
-        ASSERT_EQ("", testing::testresult::error);
+        ASSERT_EQ(std::string(), testing::testresult::error.String());
         ASSERT_TRUE(res);
         free(res);
     }
 
     // But none with an existing client name
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     res = toggl_create_client(app.ctx(),
                               wid,
                               client_name);
     ASSERT_FALSE(res);
-    ASSERT_EQ("Client name already exists", testing::testresult::error);
+    ASSERT_EQ("Client name already exists", testing::testresult::error.String());
 }
 
 TEST(toggl_api, toggl_continue) {
@@ -1057,7 +1057,7 @@ TEST(toggl_api, toggl_continue) {
     auto te = testing::testresult::time_entry_by_id(89833438);
     std::string guid = te.GUID();
 
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     ASSERT_TRUE(toggl_continue(app.ctx(), to_char_t(guid)));
     ASSERT_NE(guid, testing::testresult::timer_state.GUID());
     ASSERT_EQ("More work", testing::testresult::timer_state.Description());
@@ -1075,7 +1075,7 @@ TEST(toggl_api, toggl_continue_in_manual_mode) {
     auto te = testing::testresult::time_entry_by_id(89833438);
     std::string guid = te.GUID();
 
-    testing::testresult::error = "";
+    testing::testresult::error = noError;
     testing::testresult::editor_state = TimeEntry();
     testing::testresult::timer_state = TimeEntry();
 
@@ -1895,7 +1895,7 @@ TEST(toggl_api, toggl_autotracker_add_rule) {
     testing::testresult::error = noError;
     rule_id = toggl_autotracker_add_rule(
         app.ctx(), STR("delfi"), existing_project_id, 0);
-    ASSERT_EQ("rule already exists", testing::testresult::error);
+    ASSERT_EQ("rule already exists", testing::testresult::error.String());
     ASSERT_FALSE(rule_id);
 
     const uint64_t existing_task_id = 1879027;
diff --git a/src/time_entry.cc b/src/time_entry.cc
index cb02acc647..76ea5ad124 100644
--- a/src/time_entry.cc
+++ b/src/time_entry.cc
@@ -75,44 +75,34 @@ bool TimeEntry::ResolveError(const error &err) {
 }
 
 bool TimeEntry::isNotFound(const error &err) const {
-    return std::string::npos != std::string(err).find(
-        "Time entry not found");
+    return err == error::kTimeEntryNotFound;
 }
 bool TimeEntry::isMissingCreatedWith(const error &err) const {
-    return std::string::npos != std::string(err).find(
-        "created_with needs to be provided an a valid string");
+    return err == error::kTimeEntryCreatedWithInvalid;
 }
 
-bool TimeEntry::userCannotAccessTheSelectedProject(
-    const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "User cannot access the selected project"));
+bool TimeEntry::userCannotAccessTheSelectedProject(const error &err) const {
+    return err == error::kCannotAccessProjectError;
 }
 
-bool TimeEntry::userCannotAccessSelectedTask(
-    const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "User cannot access selected task"));
+bool TimeEntry::userCannotAccessSelectedTask(const error &err) const {
+    return err == error::kCannotAccessTaskError;
 }
 
 bool TimeEntry::durationTooLarge(const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "Max allowed duration per 1 time entry is 999 hours"));
+    return err == error::kOverMaxDurationError;
 }
 
 bool TimeEntry::startTimeWrongYear(const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "Start time year must be between 2006 and 2030"));
+    return err == error::kInvalidStartTimeError;
 }
 
 bool TimeEntry::stopTimeMustBeAfterStartTime(const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "Stop time must be after start time"));
+    return err == error::kStartNotBeforeStopError;
 }
 
 bool TimeEntry::billableIsAPremiumFeature(const error &err) const {
-    return (std::string::npos != std::string(err).find(
-        "Billable is a premium feature"));
+    return err == error::kBillableIsAPremiumFeature;
 }
 
 void TimeEntry::DiscardAt(const Poco::Int64 at) {
diff --git a/src/timeline_uploader.cc b/src/timeline_uploader.cc
index 2f6bf2bac5..f7f7ffaaa5 100644
--- a/src/timeline_uploader.cc
+++ b/src/timeline_uploader.cc
@@ -17,8 +17,8 @@
 
 namespace toggl {
 
-Poco::Logger &TimelineUploader::logger() const {
-    return Poco::Logger::get("timeline_uploader");
+Logger TimelineUploader::logger() const {
+    return { "timeline_uploader" };
 }
 
 void TimelineUploader::sleep() {
@@ -42,12 +42,7 @@ void TimelineUploader::upload_loop_activity() {
 }
 
 error TimelineUploader::process() {
-    {
-        std::stringstream out;
-        out << "upload_loop_activity (current interval "
-            << current_upload_interval_seconds_ << "s)";
-        logger().debug(out.str());
-    }
+    logger().debug("upload_loop_activity (current interval ", current_upload_interval_seconds_, "s)");
 
     if (uploading_.isStopped()) {
         return noError;
@@ -74,12 +69,7 @@ error TimelineUploader::process() {
         return err;
     }
 
-    {
-        std::stringstream out;
-        out << "Sync of " << batch.Events().size()
-            << " event(s) was successful.";
-        logger().debug(out.str());
-    }
+    logger().debug("Sync of ", batch.Events().size(), " event(s) was successful.");
 
     reset_backoff();
 
@@ -89,10 +79,7 @@ error TimelineUploader::process() {
 error TimelineUploader::upload(TimelineBatch *batch) {
     TogglClient client;
 
-    std::stringstream ss;
-    ss << "Uploading " << batch->Events().size()
-       << " event(s) of user " << batch->UserID();
-    logger().debug(ss.str());
+    logger().debug("Uploading ", batch->Events().size(), " event(s) of user ", batch->UserID());
 
     std::string json = convertTimelineToJSON(
         batch->Events(),
@@ -136,9 +123,7 @@ void TimelineUploader::backoff() {
         logger().warning("Max upload interval reached.");
         current_upload_interval_seconds_ = kTimelineUploadMaxBackoffSeconds;
     }
-    std::stringstream out;
-    out << "Upload interval set to " << current_upload_interval_seconds_ << "s";
-    logger().debug(out.str());
+    logger().debug("Upload interval set to ", current_upload_interval_seconds_, "s");
 }
 
 void TimelineUploader::reset_backoff() {
@@ -150,11 +135,11 @@ error TimelineUploader::start() {
     try {
         uploading_.start();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -166,11 +151,11 @@ error TimelineUploader::Shutdown() {
             uploading_.wait();
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
diff --git a/src/timeline_uploader.h b/src/timeline_uploader.h
index 7bab314011..5dc4f76e2f 100644
--- a/src/timeline_uploader.h
+++ b/src/timeline_uploader.h
@@ -9,13 +9,10 @@
 #include "timeline_event.h"
 #include "timeline_notifications.h"
 #include "types.h"
+#include "util/logger.h"
 
 #include <Poco/Activity.h>
 
-namespace Poco {
-class Logger;
-}
-
 namespace toggl {
 
 std::string convertTimelineToJSON(
@@ -52,7 +49,7 @@ class TOGGL_INTERNAL_EXPORT TimelineUploader {
     void backoff();
     void reset_backoff();
 
-    Poco::Logger &logger() const;
+    Logger logger() const;
 
     error process();
     void sleep();
diff --git a/src/toggl_api.cc b/src/toggl_api.cc
index 3ebf52778f..c79494fa40 100644
--- a/src/toggl_api.cc
+++ b/src/toggl_api.cc
@@ -646,9 +646,7 @@ bool_t toggl_continue(
     void *context,
     const char_t *guid) {
 
-    std::stringstream ss;
-    ss << "toggl_continue guid=" << guid;
-    logger().debug(ss.str());
+    logger().debug("toggl_continue guid=", guid);
 
     toggl::TimeEntry *result = app(context)->Continue(to_string(guid));
     if (!result) {
@@ -691,11 +689,7 @@ void toggl_edit(
     const bool_t edit_running_entry,
     const char_t *focused_field_name) {
 
-    std::stringstream ss;
-    ss << "toggl_edit guid=" << guid
-       << ", edit_running_entry = " << edit_running_entry
-       << ", focused_field_name = " << focused_field_name;
-    logger().debug(ss.str());
+    logger().debug("toggl_edit guid=", guid, ", edit_running_entry = ", edit_running_entry, ", focused_field_name = ", focused_field_name);
 
     app(context)->OpenTimeEntryEditor(
         to_string(guid),
@@ -724,9 +718,7 @@ bool_t toggl_delete_time_entry(
     void *context,
     const char_t *guid) {
 
-    std::stringstream ss;
-    ss << "toggl_delete_time_entry guid=" << guid;
-    logger().debug(ss.str());
+    logger().debug("toggl_delete_time_entry guid=", guid);
 
     return toggl::noError == app(context)->
            DeleteTimeEntryByGUID(to_string(guid));
@@ -737,10 +729,7 @@ bool_t toggl_set_time_entry_duration(
     const char_t *guid,
     const char_t *value) {
 
-    std::stringstream ss;
-    ss  << "toggl_set_time_entry_duration guid=" << guid
-        << ", value=" << value;
-    logger().debug(ss.str());
+    logger().debug("toggl_set_time_entry_duration guid=", guid, ", value=", value);
 
     return toggl::noError == app(context)->SetTimeEntryDuration(
         to_string(guid),
diff --git a/src/toggl_api_private.cc b/src/toggl_api_private.cc
index 03d9fd95c3..0f6931dcac 100644
--- a/src/toggl_api_private.cc
+++ b/src/toggl_api_private.cc
@@ -12,7 +12,6 @@
 #include "timeline_event.h"
 #include "workspace.h"
 
-#include <Poco/Logger.h>
 #include <Poco/UnicodeConverter.h>
 
 TogglAutocompleteView *autocomplete_item_init(const toggl::view::Autocomplete &item) {
@@ -337,7 +336,7 @@ TogglTimeEntryView *time_entry_view_item_init(
     view_item->Locked = te.Locked;
 
     if (te.Error != toggl::noError) {
-        view_item->Error = copy_string(te.Error);
+        view_item->Error = copy_string(te.Error.String());
     } else {
         view_item->Error = nullptr;
     }
@@ -632,12 +631,12 @@ void timeline_event_view_clear(
     delete event_view;
 }
 
-Poco::Logger &logger() {
-    return Poco::Logger::get("toggl_api");
-}
-
 toggl::Context *app(void *context) {
     poco_check_ptr(context);
 
     return reinterpret_cast<toggl::Context *>(context);
 }
+
+toggl::Logger logger() {
+    return { "toggl_api" };
+}
diff --git a/src/toggl_api_private.h b/src/toggl_api_private.h
index 74a65d0238..3e416032df 100644
--- a/src/toggl_api_private.h
+++ b/src/toggl_api_private.h
@@ -11,10 +11,7 @@
 #include "proxy.h"
 #include "settings.h"
 #include "toggl_api.h"
-
-namespace Poco {
-class Logger;
-}
+#include "util/logger.h"
 
 namespace toggl {
 class Client;
@@ -118,7 +115,7 @@ void timeline_event_view_update_duration(TogglTimelineEventView *event_view, con
 void timeline_event_view_clear(
     TogglTimelineEventView *event_view);
 
-Poco::Logger &logger();
+toggl::Logger logger();
 
 toggl::Context *app(void *context);
 
diff --git a/src/types.h b/src/types.h
index b6646b41b2..641efd3333 100644
--- a/src/types.h
+++ b/src/types.h
@@ -5,11 +5,12 @@
 
 #include <string>
 
-namespace toggl {
+#include "util/error.h"
 
-typedef std::string error;
+namespace toggl {
 
-const error noError = "";
+typedef toggl::Error error;
+inline static const error noError = Error::kNoError;
 
 typedef std::string guid;
 }
diff --git a/src/user.cc b/src/user.cc
index a8669f99ff..a047ad2c3b 100644
--- a/src/user.cc
+++ b/src/user.cc
@@ -24,8 +24,8 @@
 #include <Poco/Crypto/CipherFactory.h>
 #include <Poco/Crypto/CipherKey.h>
 #include <Poco/Crypto/CryptoStream.h>
+#include <Poco/Crypto/CryptoException.h>
 #include <Poco/DigestStream.h>
-#include <Poco/Logger.h>
 #include <Poco/Random.h>
 #include <Poco/RandomStream.h>
 #include <Poco/SHA1Engine.h>
@@ -235,12 +235,12 @@ TimeEntry *User::Continue(
 
     TimeEntry *existing = related.TimeEntryByGUID(GUID);
     if (!existing) {
-        logger().warning("Time entry not found: " + GUID);
+        logger().warning("Time entry not found: ", GUID);
         return nullptr;
     }
 
     if (existing->DeletedAt()) {
-        logger().warning(kCannotContinueDeletedTimeEntry);
+        logger().warning(error::kCannotContinueDeletedTimeEntry);
         return nullptr;
     }
 
@@ -431,9 +431,7 @@ TimeEntry *User::DiscardTimeAt(
         return nullptr;
     }
 
-    std::stringstream ss;
-    ss << "User is discarding time entry " << guid << " at " << at;
-    logger().debug(ss.str());
+    logger().debug("User is discarding time entry ", guid, " at ", at);
 
     TimeEntry *te = related.TimeEntryByGUID(guid);
     if (te) {
@@ -534,7 +532,7 @@ void User::loadUserTagFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
@@ -570,7 +568,7 @@ void User::loadUserTaskFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
@@ -607,7 +605,7 @@ error User::LoadUserUpdateFromJSONString(
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(json, root)) {
-        return error("Failed to LoadUserUpdateFromJSONString");
+        return error::kFailedToParseData;
     }
 
     loadUserUpdateFromJSON(root);
@@ -624,11 +622,7 @@ void User::loadUserUpdateFromJSON(
 
     Poco::UTF8::toLowerInPlace(action);
 
-    std::stringstream ss;
-    ss << "Update parsed into action=" << action
-       << ", model=" + model;
-    Poco::Logger &logger = Poco::Logger::get("json");
-    logger.debug(ss.str());
+    Logger("json").debug("Update parsed into action=", action, ", model=", model);
 
     if (kModelWorkspace == model) {
         loadUserWorkspaceFromJSON(data);
@@ -655,7 +649,7 @@ void User::loadUserWorkspaceFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
     Workspace *model = related.WorkspaceByID(id);
@@ -685,26 +679,20 @@ error User::LoadUserAndRelatedDataFromJSONString(
     const bool &including_related_data) {
 
     if (json.empty()) {
-        Poco::Logger &logger = Poco::Logger::get("json");
-        logger.warning("cannot load empty JSON");
+        Logger("json").warning("cannot load empty JSON");
         return noError;
     }
 
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(json, root)) {
-        return error("Failed to LoadUserAndRelatedDataFromJSONString");
+        return error::kFailedToParseData;
     }
 
     SetSince(root["since"].asInt64());
-
-    Poco::Logger &logger = Poco::Logger::get("json");
-    std::stringstream s;
-    s << "User data as of: " << Since();
-    logger.debug(s.str());
+    Logger("json").debug("User data as of: ", Since());
 
     loadUserAndRelatedDataFromJSON(root["data"], including_related_data);
-
     return noError;
 }
 
@@ -716,13 +704,13 @@ error User::LoadWorkspacesFromJSONString(const std::string & json) {
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(json, root)) {
-        return error("Failed to LoadWorkspacessFromJSONString");
+        return error::kFailedToParseData;
     }
 
     if (root.size() == 0) {
         // Handle missing workspace issue.
         // If default wid is missing there are no workspaces
-        return error(kMissingWS); // NOLINT
+        return error::kMissingWS;
     }
 
     std::set<Poco::UInt64> alive;
@@ -742,7 +730,7 @@ error User::LoadTimeEntriesFromJSONString(const std::string & json) {
     Json::Value root;
     Json::Reader reader;
     if (!reader.parse(json, root)) {
-        return error("Failed to LoadTimeEntriesFromJSONString");
+        return error::kFailedToParseData;
     }
 
     std::set<Poco::UInt64> alive;
@@ -797,7 +785,7 @@ void User::loadUserAndRelatedDataFromJSON(
     const bool &including_related_data) {
 
     if (!data["id"].asUInt64()) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
@@ -914,7 +902,7 @@ void User::loadUserClientFromSyncJSON(
     bool addNew = false;
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
     Client *model = related.ClientByID(id);
@@ -954,7 +942,7 @@ void User::loadUserClientFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
     Client *model = related.ClientByID(id);
@@ -987,7 +975,7 @@ void User::loadUserProjectFromSyncJSON(
     bool addNew = false;
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
@@ -1033,7 +1021,7 @@ void User::loadUserProjectFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
@@ -1067,24 +1055,24 @@ bool User::SetTimeEntryID(
 
     poco_check_ptr(timeEntry);
 
-    {
-        Poco::Mutex::ScopedLock lock(loadTimeEntries_m_);
-        auto otherTimeEntry = related.TimeEntryByID(id);
-        if (otherTimeEntry) {
-            // this means that somehow we already have a time entry with the ID
-            // that was just returned from a response to time entry creation request
-            logger().error("There is already a newer version of this entry");
-
-            // clearing the GUID to make sure there's no GUID conflict
-            timeEntry->SetGUID("");
-
-            // deleting the duplicate entry
-            // this entry has no ID so the corresponding server entry will not be deleted
-            timeEntry->Delete();
-            return false;
-        }
-        timeEntry->SetID(id);
-        return true;
+    {
+        Poco::Mutex::ScopedLock lock(loadTimeEntries_m_);
+        auto otherTimeEntry = related.TimeEntryByID(id);
+        if (otherTimeEntry) {
+            // this means that somehow we already have a time entry with the ID
+            // that was just returned from a response to time entry creation request
+            logger().error("There is already a newer version of this entry");
+
+            // clearing the GUID to make sure there's no GUID conflict
+            timeEntry->SetGUID("");
+
+            // deleting the duplicate entry
+            // this entry has no ID so the corresponding server entry will not be deleted
+            timeEntry->Delete();
+            return false;
+        }
+        timeEntry->SetID(id);
+        return true;
     }
 }
 
@@ -1096,13 +1084,13 @@ void User::loadUserTimeEntryFromJSON(
 
     Poco::UInt64 id = data["id"].asUInt64();
     if (!id) {
-        logger().error("Backend is sending invalid data: ignoring update without an ID");  // NOLINT
+        logger().error("Backend is sending invalid data: ignoring update without an ID");
         return;
     }
 
     TimeEntry* model;
-    {
-        Poco::Mutex::ScopedLock lock(loadTimeEntries_m_);
+    {
+        Poco::Mutex::ScopedLock lock(loadTimeEntries_m_);
         model = related.TimeEntryByID(id);
 
         if (!model) {
@@ -1120,12 +1108,12 @@ void User::loadUserTimeEntryFromJSON(
             model = new TimeEntry();
             model->SetID(id);
             related.pushBackTimeEntry(model);
-        }
-
-        if (!model->ID()) {
-            // case where model was matched by GUID
-            model->SetID(id);
-        }
+        }
+
+        if (!model->ID()) {
+            // case where model was matched by GUID
+            model->SetID(id);
+        }
     }
 
     if (alive) {
@@ -1155,7 +1143,7 @@ error User::UserID(
     Json::Reader reader;
     bool ok = reader.parse(json_data_string, root);
     if (!ok) {
-        return error("error parsing UserID JSON");
+        return error::kFailedToParseData;
     }
     *result = root["data"]["id"].asUInt64();
     return noError;
@@ -1169,7 +1157,7 @@ error User::LoginToken(
     Json::Reader reader;
     bool ok = reader.parse(json_data_string, root);
     if (!ok) {
-        return error("error parsing UserID JSON");
+        return error::kFailedToParseData;
     }
     *result = root["login_token"].asString();
     return noError;
@@ -1213,13 +1201,13 @@ std::string User::generateKey(const std::string &password) {
 
 error User::SetAPITokenFromOfflineData(const std::string &password) {
     if (Email().empty()) {
-        return error("cannot decrypt offline data without an e-mail");
+        return error::kCannotDecryptOfflineDataWithoutEmail;
     }
     if (password.empty()) {
-        return error("cannot decrypt offline data without a password");
+        return error::kCannotDecryptOfflineDataWithoutPassword;
     }
     if (OfflineData().empty()) {
-        return error("cannot decrypt empty string");
+        return error::kCannotDecryptOfflineDataWhenEmpty;
     }
     try {
         Poco::Crypto::CipherFactory& factory =
@@ -1230,7 +1218,7 @@ error User::SetAPITokenFromOfflineData(const std::string &password) {
         Json::Value data;
         Json::Reader reader;
         if (!reader.parse(OfflineData(), data)) {
-            return error("failed to parse offline data");
+            return error::kFailedToParseData;
         }
 
         std::istringstream istr(data["salt"].asString());
@@ -1249,26 +1237,29 @@ error User::SetAPITokenFromOfflineData(const std::string &password) {
         pCipher = nullptr;
 
         SetAPIToken(decrypted);
+    } catch(const Poco::IOException &) {
+        return error::kInvalidPassword;
+    } catch(const Poco::Crypto::OpenSSLException &) {
+        return error::kInvalidPassword;
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
 
-error User::EnableOfflineLogin(
-    const std::string &password) {
+error User::EnableOfflineLogin(const std::string &password) {
     if (Email().empty()) {
-        return error("cannot enable offline login without an e-mail");
+        return error::kCannotEnableOfflineLoginWithoutEmail;
     }
     if (password.empty()) {
-        return error("cannot enable offline login without a password");
+        return error::kCannotEnableOfflineLoginWithoutPassword;
     }
     if (APIToken().empty()) {
-        return error("cannot enable offline login without an API token");
+        return error::kCannotEnableOfflineLoginWithoutApiToken;
     }
     try {
         Poco::Crypto::CipherFactory& factory =
@@ -1307,14 +1298,14 @@ error User::EnableOfflineLogin(
             return err;
         }
         if (token != APIToken()) {
-            return error("offline login encryption failed");
+            return error::kOfflineDecryptionFailed;
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -1339,9 +1330,7 @@ void User::MarkTimelineBatchAsUploaded(
         TimelineEvent event = *i;
         TimelineEvent *uploaded = related.TimelineEventByGUID(event.GUID());
         if (!uploaded) {
-            logger().error(
-                "Could not find timeline event to mark it as uploaded: "
-                + event.String());
+            logger().error("Could not find timeline event to mark it as uploaded: ", event.String());
             continue;
         }
         uploaded->SetUploaded(true);
@@ -1364,15 +1353,10 @@ void User::CompressTimeline() {
 
     time_t start = time(nullptr);
 
-    {
-        std::stringstream ss;
-        ss << "CompressTimeline "
-           << " user_id=" << ID()
-           << " chunk_up_to=" << chunk_up_to
-           << " number of events=" << related.TimelineEvents.size();
-
-        logger().debug(ss.str());
-    }
+    logger().debug("CompressTimeline ",
+                   " user_id=", ID(),
+                   " chunk_up_to=", chunk_up_to,
+                   " number of events=", related.TimelineEvents.size());
 
     for (std::vector<TimelineEvent *>::iterator i =
         related.TimelineEvents.begin();
@@ -1445,16 +1429,8 @@ void User::CompressTimeline() {
         compressed[key] = chunk;
     }
 
-    {
-        std::stringstream ss;
-        ss << "CompressTimeline done in " << (time(nullptr) - start)
-           << " seconds, "
-           << related.TimelineEvents.size()
-           << " compressed into "
-           << compressed.size()
-           << " chunks";
-        logger().debug(ss.str());
-    }
+    logger().debug("CompressTimeline done in ", (time(nullptr) - start), " seconds, ",
+                   related.TimelineEvents.size(), " compressed into ", compressed.size(), " chunks");
 }
 
 std::vector<TimelineEvent> User::CompressedTimelineForUI(const Poco::LocalDateTime *date) const {
diff --git a/src/util/error.cc b/src/util/error.cc
new file mode 100644
index 0000000000..9473432c97
--- /dev/null
+++ b/src/util/error.cc
@@ -0,0 +1,365 @@
+// Copyright 2020 Toggl Desktop developers
+
+#include "error.h"
+#include "util/logger.h"
+#include "const.h"
+
+#include <set>
+
+namespace toggl {
+
+std::string Error::String() const {
+    try {
+        return values.at(code_);
+    }
+    catch (std::out_of_range &) {
+        return "Unknown error (" + std::to_string(code_) + ")";
+    }
+}
+
+Error Error::fromString(const std::string &message) {
+    for (int i = kNoError; i < kLastErrorCode; i++) {
+        auto c = static_cast<Code>(i);
+        if (Error(c).String() == message)
+            return c;
+    }
+    return kInvalidError;
+}
+
+bool Error::operator==(const Error::Code &c) const { return code_ == c; }
+bool Error::operator!=(const Error::Code &c) const { return code_ != c; }
+bool Error::operator==(const Error &o) const { return code_ == o.code_; }
+bool Error::operator!=(const Error &o) const { return code_ != o.code_; }
+
+bool Error::operator<(const Error &rhs) const {
+    return code_ < rhs.code_;
+}
+
+Error &Error::operator=(Error::Code &c) {
+    code_ = c;
+    return *this;
+}
+
+bool Error::IsNoError() const {
+    return code_ == kNoError;
+}
+
+bool Error::isValid() const {
+    return code_ >= kNoError;
+}
+
+bool Error::IsNetworkingError() const {
+    if (IsNoError()) {
+        return false;
+    }
+    if (code_ == kCannotConnectError) {
+        return true;
+    }
+    if (code_ == kBackendIsDownError) {
+        return true;
+    }
+    if (code_ == kCannotEstablishProxyConnection) {
+        return true;
+    }
+    if (code_ == kCertificateVerifyFailed) {
+        return true;
+    }
+    if (code_ == kProxyAuthenticationRequired) {
+        return true;
+    }
+    if (code_ == kCertificateValidationError) {
+        return true;
+    }
+    if (code_ == kUnacceptableCertificate) {
+        return true;
+    }
+    if (code_ == kCannotUpgradeToWebSocketConnection) {
+        return true;
+    }
+    if (code_ == kSSLException) {
+        return true;
+    }
+    /* TODO
+        if (err.find("Cannot assign requested address") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Host not found") != std::string::npos) {
+            return true;
+        }
+        if (err.find("No message received") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Connection refused") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Connection timed out") != std::string::npos) {
+            return true;
+        }
+        if (err.find("connect timed out") != std::string::npos) {
+            return true;
+        }
+        if (err.find("SSL connection unexpectedly closed") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Network is down") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Network is unreachable") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Host is down") != std::string::npos) {
+            return true;
+        }
+        if (err.find("No route to host") != std::string::npos) {
+            return true;
+        }
+        if ((err.find("I/O error: 1") != std::string::npos)
+                && (err.find(":443") != std::string::npos)) {
+            return true;
+        }
+        if (err.find("The request timed out") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Could not connect to the server") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Connection reset by peer") != std::string::npos) {
+            return true;
+        }
+        if (err.find("The Internet connection appears to be offline")
+                != std::string::npos) {
+            return true;
+        }
+        if (err.find("Timeout") != std::string::npos) {
+            return true;
+        }
+        if (err.find("An internal server error occurred.") != std::string::npos) {
+            return true;
+        }
+        */
+    return false;
+}
+
+bool Error::IsUserError() const {
+    if (IsNoError()) {
+        return false;
+    }
+    if (code_ == kErrorRuleAlreadyExists) {
+        return true;
+    }
+    if (code_ == kCheckYourSignupError) {
+        return true;
+    }
+    if (code_ == kEmailNotFoundCannotLogInOffline) {
+        return true;
+    }
+    if (code_ == kInvalidPassword) {
+        return true;
+    }
+    if (code_ == kPaymentRequiredError) {
+        return true;
+    }
+    if (code_ == kBadRequestError) {
+        return true;
+    }
+    if (code_ == kUnauthorizedError) {
+        return true;
+    }
+    if (code_ == kCannotWriteFile) {
+        return true;
+    }
+    if (code_ == kIsSuspended) {
+        return true;
+    }
+    if (code_ == kRequestToServerFailedWithStatusCode403) {
+        return true;
+    }
+    if (code_ == kUnsupportedAppError) {
+        return true;
+    }
+    if (code_ == kMissingWorkspaceID) {
+        return true;
+    }
+    if (code_ == kEndpointGoneError) {
+        return true;
+    }
+    if (code_ == kCannotAccessWorkspaceError) {
+        return true;
+    }
+    if (code_ == kCannotSyncInTestEnv) {
+        return true;
+    }
+    if (code_ == kCannotContinueDeletedTimeEntry) {
+        return true;
+    }
+    if (code_ == kCannotDeleteDeletedTimeEntry) {
+        return true;
+    }
+    if (code_ == kPleaseSelectAWorkspace) {
+        return true;
+    }
+    if (code_ == kClientNameMustNotBeEmpty) {
+        return true;
+    }
+    if (code_ == kProjectNameMustNotBeEmpty) {
+        return true;
+    }
+    if (code_ == kClientNameAlreadyExists) {
+        return true;
+    }
+    if (code_ == kProjectNameAlreadyExists) {
+        return true;
+    }
+    if (code_ == kThisEntryCantBeSavedPleaseAdd) {
+        return true;
+    }
+    /* TODO
+        if (err.find("File not found") != std::string::npos) {
+            return true;
+        }
+        if (err.find("SSL context exception") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Access to file denied") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Stop time must be after start time")
+                != std::string::npos) {
+            return true;
+        }
+        if (err.find("Invalid e-mail or password") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Maximum length for description") != std::string::npos) {
+            return true;
+        }
+        if (err.find("Start time year must be between 2010 and 2100")
+                != std::string::npos) {
+            return true;
+        }
+        if (err.find("Password should be at least") != std::string::npos) {
+            return true;
+        }
+        if (err.find("User with this email already exists") !=
+                std::string::npos) {
+            return true;
+        }
+        if (err.find("Invalid e-mail") != std::string::npos) {
+            return true;
+        }
+        */
+    return false;
+}
+
+std::string Error::MakeErrorActionable() const {
+    if (IsNoError()) {
+        return String();
+    }
+    if (code_ == kCannotEstablishProxyConnection) {
+        return Error(kCheckYourProxySetup).String();
+    }
+    if (code_ == kCertificateVerifyFailed) {
+        return Error(kCheckYourFirewall).String();
+    }
+    if (code_ == kProxyAuthenticationRequired) {
+        return Error(kCheckYourProxySetup).String();
+    }
+    if (code_ == kCertificateValidationError) {
+        return Error(kCheckYourFirewall).String();
+    }
+    if (code_ == kUnacceptableCertificate) {
+        return Error(kCheckYourFirewall).String();
+    }
+    if (code_ == kCannotUpgradeToWebSocketConnection) {
+        return Error(kCheckYourFirewall).String();
+    }
+    if (code_ == kSSLException) {
+        return Error(kCheckYourFirewall).String();
+    }
+    if (code_ == kCannotWriteFile) {
+        return "Check your user permissions";
+    }
+    if (code_ == kIsSuspended) {
+        return "The workspace is suspended, please check your payments";
+    }
+    if (code_ == kRequestToServerFailedWithStatusCode403) {
+        return "You do not have access to this workspace";
+    }
+    if (code_ == kMissingWorkspaceID) {
+        return "Please select a project";
+    }
+    if (code_ == kDatabaseDiskMalformed) {
+        return "Local database is corrupt. Please clear local data to recreate local database.";
+    }
+    if (code_ == kEndpointGoneError) {
+        return Error(kOutOfDatePleaseUpgrade).String();
+    }
+    return String();
+}
+
+Error Error::fromHttpStatus(Poco::Net::HTTPResponse::HTTPStatus http_status) {
+    return fromHttpStatus((int64_t) http_status);
+}
+
+Error Error::fromHttpStatus(int64_t http_status) {
+    switch (http_status) {
+    case 200:
+    case 201:
+    case 202:
+        return kNoError;
+    case 400:
+        // data that you sending is not valid/acceptable
+        return kBadRequestError;
+    case 401:
+        // ask user to enter login again, do not obtain new token automatically
+        return kUnauthorizedError;
+    case 402:
+        // requested action allowed only for pro workspace show user upsell
+        // page / ask for workspace pro upgrade. do not retry same request
+        // unless known that client is pro
+        return kPaymentRequiredError;
+    case 403:
+        // client has no right to perform given request. Server
+        return kForbiddenError;
+    case 404:
+        // request is not possible
+        // (or not allowed and server does not tell why)
+        return kRequestIsNotPossible;
+    case 410:
+        return kEndpointGoneError;
+    case 418:
+        return kUnsupportedAppError;
+    case 429:
+        return kCannotConnectError;
+    case 500:
+    case 501:
+    case 502:
+    case 503:
+    case 504:
+    case 505:
+        return kBackendIsDownError;
+    default: {
+        Logger("error").error("Unexpected HTTP status code: " + std::to_string(http_status));
+        return kCannotConnectError;
+    }
+    }
+}
+
+Error Error::fromServerError(const std::string &message) {
+    const static std::set<Code> codes {
+        kTimeEntryNotFound, kTimeEntryCreatedWithInvalid, kCannotAccessProjectError, kCannotAccessTaskError,
+        kOverMaxDurationError, kInvalidStartTimeError, kStartNotBeforeStopError, kBillableIsAPremiumFeature
+    };
+    for (auto i : codes) {
+        if (message.find(Error(i).String()) != std::string::npos)
+            return i;
+    }
+    return kNoError;
+}
+
+std::ostream &operator<<(std::ostream &out, const Error &t) {
+    out << t.String();
+    return out;
+}
+
+} // namespace toggl
diff --git a/src/util/error.h b/src/util/error.h
new file mode 100644
index 0000000000..a1fb199f9d
--- /dev/null
+++ b/src/util/error.h
@@ -0,0 +1,260 @@
+// Copyright 2020 Toggl Desktop developers
+
+#ifndef ERROR_H
+#define ERROR_H
+
+#include "logger.h"
+
+#include <string>
+#include <map>
+
+#include <Poco/Net/HTTPResponse.h>
+
+namespace toggl {
+
+class Error {
+public:
+    enum Code {
+        kInvalidError = -1,
+        kNoError = 0,
+
+        kOverMaxDurationError,
+        kMaxTagsPerTimeEntryError,
+        kInvalidStartTimeError,
+        kInvalidStopTimeError,
+        kInvalidDateError,
+        kStartNotBeforeStopError,
+        kMaximumDescriptionLengthError,
+
+        kCheckYourSignupError,
+        kEndpointGoneError,
+        kForbiddenError,
+        kUnsupportedAppError,
+        kUnauthorizedError,
+        kCannotConnectError,
+        kCannotSyncInTestEnv,
+        kBackendIsDownError,
+        kBadRequestError,
+        kRequestIsNotPossible,
+        kPaymentRequiredError,
+        kCannotAccessWorkspaceError,
+        kEmailNotFoundCannotLogInOffline,
+        kEmptyEmail,
+        kEmptyPassword,
+        kInvalidPassword,
+        kMissingApiToken,
+        kCannotEstablishProxyConnection,
+        kCertificateVerifyFailed,
+        kCheckYourProxySetup,
+        kCheckYourFirewall,
+        kProxyAuthenticationRequired,
+        kCertificateValidationError,
+        kUnacceptableCertificate,
+        kMissingCACertificate,
+        kCannotUpgradeToWebSocketConnection,
+        kSSLException,
+        kRateLimit,
+        kCannotWriteFile,
+        kIsSuspended,
+        kRequestToServerFailedWithStatusCode403,
+        kMissingWorkspaceID,
+        kCannotContinueDeletedTimeEntry,
+        kCannotDeleteDeletedTimeEntry,
+        kErrorRuleAlreadyExists,
+        kPleaseSelectAWorkspace,
+        kClientNameMustNotBeEmpty,
+        kProjectNameMustNotBeEmpty,
+        // kProjectNameAlready, // huh, what is this?
+        kProjectNameAlreadyExists,
+        kClientNameAlreadyExists,
+        kDatabaseDiskMalformed,
+        kMissingWS,
+        kOutOfDatePleaseUpgrade,
+        kThisEntryCantBeSavedPleaseAdd,
+
+        // these were hardcoded as strings
+        kFailedToParseData,
+        kExportWithoutGUID,
+        kDeleteRuleWithoutID,
+        kNameAlreadyTaken, // is this the same as kClientNameAlreadyExists?
+        kCannotModifyWorkspaceData,
+        kMissingFeedbackTopic,
+        kMissingFeedbackDetails,
+        kMissingUICallbacks,
+        kCannotCheckForUpdates,
+        kInvalidUpdateChannel,
+        kCannotChangeLockedTE,
+        kInvalidTimeFormat,
+        kCannotCreateObmAction,
+        kCannotStartAutotrackerEvent,
+
+        kTimeEntryNotFound,
+        kTimeEntryCreatedWithInvalid,
+        kCannotAccessProjectError, // should these be a single error?
+        kCannotAccessTaskError,
+        kBillableIsAPremiumFeature, // should this be the same as kPaymentRequiredError?
+
+        kMissingArgument, // I don't think more info is necessary about WHAT argument is missing
+
+        kTimeEntryWouldBeLockedAfterProjectChange,
+
+        kOfflineLoginMissingEmail,
+        kOfflineLoginMissingPassword,
+        kCannotLoadUserDataWhenLoggedOut,
+        kCannotLoadUserDataWithoutApiToken,
+        kCannotSaveUserDataWhenLoggedOut,
+        kCannotSaveUserDataWithoutApiToken,
+
+        kBackendChangedTheID,
+        kClientIsNotPresentInWorkspace,
+        kOnlyAdminsCanChangeVisibility,
+
+        kCannotDecryptOfflineDataWithoutEmail,
+        kCannotDecryptOfflineDataWithoutPassword,
+        kCannotDecryptOfflineDataWhenEmpty,
+        kCannotEnableOfflineLoginWithoutEmail,
+        kCannotEnableOfflineLoginWithoutPassword,
+        kCannotEnableOfflineLoginWithoutApiToken,
+        kOfflineDecryptionFailed,
+
+        kWebsocketClosedConnection,
+
+
+        // REMOVE THESE WHEN COMMITTING
+        REMOVE_LATER_BATCH_UPDATE_ERROR,
+        REMOVE_LATER_EXCEPTION_HANDLER,
+        REMOVE_LATER_NETWORK_RESPONSE,
+        REMOVE_LATER_DATABASE_LAST_ERROR,
+        REMOVE_LATER_DATABASE_STORE_ERROR,
+        REMOVE_LATER_CLIENT_NOT_PRESENT_WITH_ID,
+
+        kLastErrorCode
+    };
+    inline static const std::map<Code, std::string> values {
+        { kNoError, {} },
+
+        { kOverMaxDurationError, "Max allowed duration per 1 time entry is 999 hours" },
+        { kMaxTagsPerTimeEntryError, "Tags are limited to 50 per task" },
+        { kInvalidStartTimeError, "Start time year must be between 2006 and 2030" },
+        { kInvalidStopTimeError, "Stop time year must be between 2006 and 2030" },
+        { kInvalidDateError, "Date year must be between 2006 and 2030" },
+        { kStartNotBeforeStopError, "Stop time must be after start time" },
+        { kMaximumDescriptionLengthError, "Maximum length for description (3000 chars) exceeded" },
+
+        { kCheckYourSignupError, "Signup failed - please check your details. The e-mail might be already taken." },
+        { kEndpointGoneError, "The API endpoint used by this app is gone. Please contact Toggl support!" },
+        { kForbiddenError, "Invalid e-mail or password!" },
+        { kUnsupportedAppError, "This version of the app is not supported any more. Please visit Toggl website to download a supported app." },
+        { kUnauthorizedError, "Unauthorized! Please login again." },
+        { kCannotConnectError, "Cannot connect to Toggl" },
+        { kCannotSyncInTestEnv, "Cannot sync in test env" },
+        { kBackendIsDownError, "Backend is down" },
+        { kBadRequestError, "Data that you are sending is not valid/acceptable" },
+        { kRequestIsNotPossible, "Request is not possible" },
+        { kPaymentRequiredError, "Requested action allowed only for Non-Free workspaces. Please upgrade!" },
+        { kCannotAccessWorkspaceError, "cannot access workspace" },
+        { kEmailNotFoundCannotLogInOffline, "Login failed. Are you online?" },
+        { kInvalidPassword, "Invalid password" },
+        { kMissingApiToken, "cannot pull user data without API token" },
+        { kCannotEstablishProxyConnection, "Cannot establish proxy connection" },
+        { kCertificateVerifyFailed, "certificate verify failed" },
+        { kCheckYourProxySetup, "Check your proxy setup" },
+        { kCheckYourFirewall, "Check your firewall" },
+        { kProxyAuthenticationRequired, "Proxy Authentication Required" },
+        { kCertificateValidationError, "Certificate validation error" },
+        { kUnacceptableCertificate, "Unacceptable certificate from www.toggl.com" },
+        { kMissingCACertificate, "Missing CA certifcate, cannot start Websocket" },
+        { kCannotUpgradeToWebSocketConnection, "Cannot upgrade to WebSocket connection" },
+        { kSSLException, "SSL Exception" },
+        { kRateLimit, "Too many requests, sync delayed by 1 minute" },
+        { kCannotWriteFile, "Cannot write file" },
+        { kIsSuspended, "is suspended" },
+        { kRequestToServerFailedWithStatusCode403, "Request to server failed with status code: 403" },
+        { kMissingWorkspaceID, "Missing workspace ID" },
+        { kCannotContinueDeletedTimeEntry, "Cannot continue deleted time entry" },
+        { kCannotDeleteDeletedTimeEntry, "Cannot delete deleted time entry" },
+        { kErrorRuleAlreadyExists, "rule already exists" },
+        { kPleaseSelectAWorkspace, "Please select a workspace" },
+        { kClientNameMustNotBeEmpty, "Client name must not be empty" },
+        { kProjectNameMustNotBeEmpty, "Project name must not be empty" },
+        //{ kProjectNameAlready, "Project name already" },
+        { kProjectNameAlreadyExists, "Project name already exists" },
+        { kClientNameAlreadyExists, "Client name already exists" },
+        { kDatabaseDiskMalformed, "The database disk image is malformed" },
+        { kMissingWS, "You no longer have access to your last workspace" },
+        { kOutOfDatePleaseUpgrade, "Your version of Toggl Desktop is out of date, please upgrade!" },
+        { kThisEntryCantBeSavedPleaseAdd, "This entry can't be saved - please add" },
+
+        { kFailedToParseData, "Failed to parse data string" },
+        { kExportWithoutGUID, "Cannot export model to batch update without a GUID" },
+        { kDeleteRuleWithoutID, "cannot delete rule without an ID" },
+        { kNameAlreadyTaken, "Name has already been taken" },
+        { kCannotModifyWorkspaceData, "User cannot add or edit clients in workspace" },
+        { kMissingFeedbackTopic, "Missing topic" },
+        { kMissingFeedbackDetails, "Missing details" },
+        { kMissingUICallbacks, "UI is not properly wired up!"},
+        { kCannotCheckForUpdates, "This version cannot check for updates. This has been probably already fixed. Please check https://toggl.com/toggl-desktop/ for a newer version." },
+        { kInvalidUpdateChannel, "Invalid update channel" },
+        { kCannotChangeLockedTE, "Cannot change locked time entry." },
+        { kInvalidTimeFormat, "invalid time format" },
+
+        { kTimeEntryNotFound, "Time entry not found" },
+        { kTimeEntryCreatedWithInvalid, "created_with needs to be provided an a valid string" },
+        { kCannotAccessProjectError, "User cannot access the selected project" },
+        { kCannotAccessTaskError, "User cannot access selected task" },
+        { kBillableIsAPremiumFeature, "Billable is a premium feature" },
+
+        { kTimeEntryWouldBeLockedAfterProjectChange, "Cannot change project: would end up with locked time entry" },
+
+        { kOfflineLoginMissingEmail, "cannot login offline without an e-mail" },
+        { kOfflineLoginMissingPassword, "cannot login offline without a password" },
+        { kCannotLoadUserDataWhenLoggedOut, "cannot load user data when logged out" },
+        { kCannotLoadUserDataWithoutApiToken, "cannot pull user data without API token" },
+        { kCannotSaveUserDataWhenLoggedOut, "cannot push changes when logged out"},
+        { kCannotSaveUserDataWithoutApiToken, "cannot push changes without API token"},
+
+        { kBackendChangedTheID, "Backend has changed the ID of the entry" },
+        { kClientIsNotPresentInWorkspace, "client is in another workspace" },
+        { kOnlyAdminsCanChangeVisibility, "Only admins can change project visibility" },
+
+        { kCannotDecryptOfflineDataWithoutEmail, "cannot decrypt offline data without an e-mail" },
+        { kCannotDecryptOfflineDataWithoutPassword, "cannot decrypt offline data without a password" },
+        { kCannotDecryptOfflineDataWhenEmpty, "cannot decrypt empty string" },
+        { kCannotEnableOfflineLoginWithoutEmail, "cannot enable offline login without an e-mail" },
+        { kCannotEnableOfflineLoginWithoutPassword, "cannot enable offline login without a password" },
+        { kCannotEnableOfflineLoginWithoutApiToken, "cannot enable offline login without an API token" },
+        { kOfflineDecryptionFailed, "offline login encryption failed" },
+
+        { kWebsocketClosedConnection, "WebSocket closed the connection" },
+    };
+
+    Error(Code c) : code_(c) {}
+    bool operator==(const Code &c) const;
+    bool operator!=(const Code &c) const;
+    bool operator==(const Error &o) const;
+    bool operator!=(const Error &o) const;
+    bool operator<(const Error &rhs) const;
+    Error &operator=(Code &c);
+
+    bool IsNoError() const;
+    bool isValid() const;
+    bool IsNetworkingError() const;
+    bool IsUserError() const;
+
+    std::string MakeErrorActionable() const;
+    std::string String() const;
+
+    static Error fromString(const std::string &message);
+
+    static Error fromHttpStatus(Poco::Net::HTTPResponse::HTTPStatus http_status);
+    static Error fromHttpStatus(int64_t http_status);
+    static Error fromServerError(const std::string &message);
+private:
+    Code code_;
+};
+
+std::ostream &operator<<(std::ostream &out, const Error &t);
+
+} // namespace toggl
+
+#endif // ERROR_H
diff --git a/src/util/logger.cc b/src/util/logger.cc
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/src/util/logger.h b/src/util/logger.h
new file mode 100644
index 0000000000..58b451c4f8
--- /dev/null
+++ b/src/util/logger.h
@@ -0,0 +1,75 @@
+// Copyright 2020 Toggl Desktop developers.
+
+#ifndef SRC_LOGGER_H_
+#define SRC_LOGGER_H_
+
+#include <Poco/Logger.h>
+#include <string>
+#include <utility>
+#include <sstream>
+
+namespace toggl {
+
+/*
+ * Beware, template black magic ahead
+ *
+ * Use Logger like this:
+ *  Logger logger("myclass");
+ *  logger.log("Running sync", foo, bar, "baz", 123);
+ * and as long as all of the used types have a stringstream conversion, it'll run.
+ * You can also declare your own stringstream << operator if you want to debug custom classes.
+ */
+class Logger {
+public:
+    Logger(const std::string &context)
+        : context_(context)
+    {}
+
+    template <typename... Args>
+    void trace(Args&&... args) const {
+        std::stringstream ss;
+        prepareOutput(ss, std::forward<Args>(args)...);
+        Poco::Logger::get(context_).trace(ss.str());
+    }
+    template <typename... Args>
+    void log(Args&&... args) const {
+        std::stringstream ss;
+        prepareOutput(ss, std::forward<Args>(args)...);
+        Poco::Logger::get(context_).log(ss.str());
+    }
+    template <typename... Args>
+    void debug(Args&&... args) const {
+        std::stringstream ss;
+        prepareOutput(ss, std::forward<Args>(args)...);
+        Poco::Logger::get(context_).debug(ss.str());
+    }
+    template <typename... Args>
+    void warning(Args&&... args) const {
+        std::stringstream ss;
+        prepareOutput(ss, std::forward<Args>(args)...);
+        Poco::Logger::get(context_).warning(ss.str());
+    }
+    template <typename... Args>
+    void error(Args&&... args) const {
+        std::stringstream ss;
+        prepareOutput(ss, std::forward<Args>(args)...);
+        Poco::Logger::get(context_).error(ss.str());
+    }
+
+private:
+    template <typename Arg>
+    void prepareOutput(std::stringstream &ss, Arg&& arg) const {
+        ss << std::forward<Arg>(arg);
+    }
+    template <typename Arg, typename... Args>
+    void prepareOutput(std::stringstream &ss, Arg&& arg, Args&&... args) const {
+        ss << std::forward<Arg>(arg);
+        prepareOutput(ss, std::forward<Args>(args)...);
+    }
+private:
+    std::string context_;
+};
+
+} // namespace toggl
+
+#endif // SRC_LOGGER_H_
diff --git a/src/websocket_client.cc b/src/websocket_client.cc
index 94b74ff6da..dbc956fbb0 100644
--- a/src/websocket_client.cc
+++ b/src/websocket_client.cc
@@ -77,7 +77,7 @@ error WebSocketClient::createSession() {
     logger().debug("createSession");
 
     if (HTTPSClient::Config.CACertPath.empty()) {
-        return error("Missing CA certifcate, cannot start Websocket");
+        return error::kMissingCACertificate;
     }
 
     Poco::Mutex::ScopedLock lock(mutex_);
@@ -88,10 +88,7 @@ error WebSocketClient::createSession() {
 
     error err = TogglClient::TogglStatus.Status();
     if (err != noError) {
-        std::stringstream ss;
-        ss << "Will not start Websocket sessions, ";
-        ss << "because of known bad Toggl status: " << err;
-        logger().error(ss.str());
+        logger().error("Will not start Websocket sessions, ", "because of known bad Toggl status: ", err);
         return err;
     }
 
@@ -135,11 +132,11 @@ error WebSocketClient::createSession() {
 
         authenticate();
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
 
     return noError;
@@ -192,11 +189,11 @@ error WebSocketClient::receiveWebSocketMessage(std::string *message) {
             json.append(buf, static_cast<unsigned>(n));
         }
     } catch(const Poco::Exception& exc) {
-        return error(exc.displayText());
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return error(ex.what());
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return error(ex);
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     *message = json;
     return noError;
@@ -217,11 +214,9 @@ error WebSocketClient::poll() {
             return err;
         }
         if (json.empty()) {
-            return error("WebSocket closed the connection");
+            return error::kWebsocketClosedConnection;
         }
-        std::stringstream ss;
-        ss << "WebSocket message: " << json;
-        logger().trace(ss.str());
+        logger().trace("WebSocket message: ", json);
 
         last_connection_at_ = time(nullptr);
 
@@ -242,11 +237,11 @@ error WebSocketClient::poll() {
             on_websocket_message_(ctx_, json);
         }
     } catch(const Poco::Exception& exc) {
-        return error(exc.displayText());
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return error(ex.what());
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return error(ex);
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
@@ -317,15 +312,13 @@ void WebSocketClient::deleteSession() {
     logger().debug("session deleted");
 }
 
-Poco::Logger &WebSocketClient::logger() const {
-    return Poco::Logger::get("websocket_client");
+Logger WebSocketClient::logger() const {
+    return { "websocket_client" };
 }
 
 int WebSocketClient::nextWebsocketRestartInterval() {
     int res = static_cast<int>(Random::next(kWebsocketRestartRangeSeconds)) + 1;
-    std::stringstream ss;
-    ss << "Next websocket restart in " << res << " seconds";
-    logger().trace(ss.str());
+    logger().trace("Next websocket restart in ", res, " seconds");
     return res;
 }
 
diff --git a/src/websocket_client.h b/src/websocket_client.h
index 3e5bc730ed..17b5d2d486 100644
--- a/src/websocket_client.h
+++ b/src/websocket_client.h
@@ -10,17 +10,16 @@
 #include <Poco/Activity.h>
 
 #include "types.h"
+#include "util/logger.h"
 
 namespace Poco {
-class Logger;
-
-namespace Net {
-class HTTPSClientSession;
-class HTTPRequest;
-class HTTPResponse;
-class WebSocket;
-}
-}
+    namespace Net {
+        class HTTPSClientSession;
+        class HTTPRequest;
+        class HTTPResponse;
+        class WebSocket;
+    } // namespace Poco::Net
+} // namespace Poco
 
 namespace toggl {
 
@@ -66,7 +65,7 @@ class TOGGL_INTERNAL_EXPORT WebSocketClient {
 
     int nextWebsocketRestartInterval();
 
-    Poco::Logger &logger() const;
+    Logger logger() const;
 
     Poco::Activity<WebSocketClient> activity_;
     Poco::Net::HTTPSClientSession *session_;
diff --git a/src/window_change_recorder.cc b/src/window_change_recorder.cc
index 9e3acf854d..7a5f713028 100644
--- a/src/window_change_recorder.cc
+++ b/src/window_change_recorder.cc
@@ -7,7 +7,6 @@
 #include "get_focused_window.h"
 #include "const.h"
 
-#include <Poco/Logger.h>
 #include <Poco/Thread.h>
 
 #if defined(__APPLE__)
@@ -16,10 +15,6 @@ extern bool isCatalinaOSX(void);
 
 namespace toggl {
 
-Poco::Logger &WindowChangeRecorder::logger() {
-    return Poco::Logger::get("WindowChangeRecorder");
-}
-
 bool WindowChangeRecorder::hasWindowChanged(
     const std::string &title,
     const std::string &filename) const {
@@ -41,9 +36,7 @@ void WindowChangeRecorder::inspectFocusedWindow() {
         int count = 1;
 
         if (it == timeline_errors_.end()) {
-            std::stringstream ss;
-            ss << "Failed to get focused window info, error code: " << err;
-            logger().error(ss.str());
+            logger.error("Failed to get focused window info, error code: ", err);
         } else {
             count += timeline_errors_[err];
         }
@@ -51,10 +44,7 @@ void WindowChangeRecorder::inspectFocusedWindow() {
         timeline_errors_[err] = count;
 
         if (count % 100 == 0) {
-            std::stringstream ss;
-            ss << "Failed to get focused window info, error code: "
-               << err << " [" << count << " times]";
-            logger().error(ss.str());
+            logger.error("Failed to get focused window info, error code: ", err, " [", count, " times]");
         }
 
         // Allow erroneous timeline event in Windows
@@ -126,7 +116,7 @@ void WindowChangeRecorder::inspectFocusedWindow() {
             event->SetIdle(false);
             error err = timeline_datasource_->StartTimelineEvent(event);
             if (err != noError) {
-                logger().error(err);
+                logger.error(err);
             }
         }
     }
@@ -175,11 +165,11 @@ error WindowChangeRecorder::Shutdown() {
             recording_.wait(5);
         }
     } catch(const Poco::Exception& exc) {
-        return exc.displayText();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::exception& ex) {
-        return ex.what();
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     } catch(const std::string & ex) {
-        return ex;
+        return error::REMOVE_LATER_EXCEPTION_HANDLER;
     }
     return noError;
 }
diff --git a/src/window_change_recorder.h b/src/window_change_recorder.h
index f7576f35f5..d47c9c4292 100644
--- a/src/window_change_recorder.h
+++ b/src/window_change_recorder.h
@@ -8,6 +8,7 @@
 
 #include "timeline_notifications.h"
 #include "types.h"
+#include "util/logger.h"
 
 #include <Poco/Activity.h>
 
@@ -15,10 +16,6 @@
 extern bool isCatalinaOSX(void);
 #endif
 
-namespace Poco {
-class Logger;
-}
-
 namespace toggl {
 
 class TOGGL_INTERNAL_EXPORT WindowChangeRecorder {
@@ -73,7 +70,7 @@ class TOGGL_INTERNAL_EXPORT WindowChangeRecorder {
 
     bool hasIdlenessChanged(const bool &idle) const;
 
-    Poco::Logger &logger();
+    Logger logger { "WindowChangeRecorder" };
 
     bool getIsLocked() {
         Poco::Mutex::ScopedLock lock(isLocked_m_);