diff --git a/CHANGELOG-WIP.md b/CHANGELOG-WIP.md
index db461cb6f4f..772eff76579 100644
--- a/CHANGELOG-WIP.md
+++ b/CHANGELOG-WIP.md
@@ -51,6 +51,7 @@
 - Element query date params now support passing `today`, `tomorrow`, and `yesterday`. ([#10485](https://github.com/craftcms/cms/issues/10485))
 - Element queries now support passing ambiguous column names (e.g. `dateCreated`) and field handles into `select()`. ([#11790](https://github.com/craftcms/cms/pull/11790), [#11800](https://github.com/craftcms/cms/pull/11800))
 - `{% cache %}` tags now store any HTML registered with `{% html %}` tags. ([#11811](https://github.com/craftcms/cms/discussions/11811))
+- Control panel `.twig` templates are now prioritized over `.html`. ([#11809](https://github.com/craftcms/cms/discussions/11809), [#11840](https://github.com/craftcms/cms/pull/11840))
 - `craft\helpers\Component::iconSvg()` now namespaces the SVG contents, and adds `aria-hidden="true"`. ([#11703](https://github.com/craftcms/cms/pull/11703))
 - `craft\services\Search::EVENT_BEFORE_INDEX_KEYWORDS` is now cancellable by setting `$event->isValid` to `false`. ([#11705](https://github.com/craftcms/cms/discussions/11705))
 - `checkboxSelect` inputs without `showAllOption: true` now post an empty value if no options were selected. ([#11748](https://github.com/craftcms/cms/issues/11748))
diff --git a/src/assetpreviews/Image.php b/src/assetpreviews/Image.php
index a28720c44e5..e76839bb3bb 100644
--- a/src/assetpreviews/Image.php
+++ b/src/assetpreviews/Image.php
@@ -34,7 +34,7 @@ public function getPreviewHtml(array $variables = []): string
             ]);
         }
 
-        return Craft::$app->getView()->renderTemplate('assets/_previews/image',
+        return Craft::$app->getView()->renderTemplate('assets/_previews/image.twig',
             array_merge([
                 'asset' => $this->asset,
                 'url' => $url,
diff --git a/src/assetpreviews/Text.php b/src/assetpreviews/Text.php
index 4ef18e8d113..254d7c8fd77 100644
--- a/src/assetpreviews/Text.php
+++ b/src/assetpreviews/Text.php
@@ -31,7 +31,7 @@ public function getPreviewHtml(array $variables = []): string
         FileHelper::unlink($localCopy);
         $language = $this->asset->kind === Asset::KIND_HTML ? 'markup' : $this->asset->kind;
 
-        return Craft::$app->getView()->renderTemplate('assets/_previews/text',
+        return Craft::$app->getView()->renderTemplate('assets/_previews/text.twig',
             array_merge([
                 'asset' => $this->asset,
                 'language' => $language,
diff --git a/src/assetpreviews/Video.php b/src/assetpreviews/Video.php
index 4ebad587732..510e2fd5380 100644
--- a/src/assetpreviews/Video.php
+++ b/src/assetpreviews/Video.php
@@ -30,7 +30,7 @@ public function getPreviewHtml(array $variables = []): string
             throw new NotSupportedException('Preview not supported.');
         }
 
-        return Craft::$app->getView()->renderTemplate('assets/_previews/video',
+        return Craft::$app->getView()->renderTemplate('assets/_previews/video.twig',
             array_merge([
                 'asset' => $this->asset,
                 'url' => $url,
diff --git a/src/base/MissingComponentTrait.php b/src/base/MissingComponentTrait.php
index 350108e6aa0..9517b1da136 100644
--- a/src/base/MissingComponentTrait.php
+++ b/src/base/MissingComponentTrait.php
@@ -128,7 +128,7 @@ public function getPlaceholderHtml(): string
             }
         }
 
-        return Craft::$app->getView()->renderTemplate('_special/missing-component', compact(
+        return Craft::$app->getView()->renderTemplate('_special/missing-component.twig', compact(
             'error',
             'showPlugin',
             'isComposerInstalled',
diff --git a/src/base/Plugin.php b/src/base/Plugin.php
index 1d1cbf0fe1d..bb7b22075fa 100644
--- a/src/base/Plugin.php
+++ b/src/base/Plugin.php
@@ -206,7 +206,7 @@ public function getSettingsResponse(): mixed
         /** @var Controller $controller */
         $controller = Craft::$app->controller;
 
-        return $controller->renderTemplate('settings/plugins/_settings', [
+        return $controller->renderTemplate('settings/plugins/_settings.twig', [
             'plugin' => $this,
             'settingsHtml' => $settingsHtml,
         ]);
diff --git a/src/controllers/AssetsController.php b/src/controllers/AssetsController.php
index a5d7f570164..bc0e8b53938 100644
--- a/src/controllers/AssetsController.php
+++ b/src/controllers/AssetsController.php
@@ -764,7 +764,7 @@ public function actionImageEditor(): Response
 
         $focal = $asset->getHasFocalPoint() ? $asset->getFocalPoint() : null;
 
-        $html = $this->getView()->renderTemplate('_special/image_editor');
+        $html = $this->getView()->renderTemplate('_special/image_editor.twig');
 
         return $this->asJson(['html' => $html, 'focalPoint' => $focal]);
     }
diff --git a/src/controllers/BaseUpdaterController.php b/src/controllers/BaseUpdaterController.php
index 8abec982600..f64909ffe0b 100644
--- a/src/controllers/BaseUpdaterController.php
+++ b/src/controllers/BaseUpdaterController.php
@@ -97,7 +97,7 @@ public function actionIndex(): Response
         $stateJs = Json::encode($state);
         $this->getView()->registerJs("Craft.updater = (new Craft.Updater($idJs)).setState($stateJs);");
 
-        return $this->renderTemplate('_special/updater', [
+        return $this->renderTemplate('_special/updater.twig', [
             'title' => $this->pageTitle(),
         ]);
     }
diff --git a/src/controllers/CategoriesController.php b/src/controllers/CategoriesController.php
index 9f2de7c9883..2ed9bf16fc1 100644
--- a/src/controllers/CategoriesController.php
+++ b/src/controllers/CategoriesController.php
@@ -58,7 +58,7 @@ public function actionGroupIndex(): Response
 
         $groups = Craft::$app->getCategories()->getAllGroups();
 
-        return $this->renderTemplate('settings/categories/index', [
+        return $this->renderTemplate('settings/categories/index.twig', [
             'categoryGroups' => $groups,
         ]);
     }
@@ -113,7 +113,7 @@ public function actionEditCategoryGroup(?int $groupId = null, ?CategoryGroup $ca
         $variables['groupId'] = $groupId;
         $variables['categoryGroup'] = $categoryGroup;
 
-        return $this->renderTemplate('settings/categories/_edit', $variables);
+        return $this->renderTemplate('settings/categories/_edit.twig', $variables);
     }
 
     /**
@@ -225,7 +225,7 @@ public function actionCategoryIndex(?string $groupHandle = null): Response
             'New category',
         ]);
 
-        return $this->renderTemplate('categories/_index', [
+        return $this->renderTemplate('categories/_index.twig', [
             'groupHandle' => $groupHandle,
             'groups' => $groups,
         ]);
@@ -549,7 +549,7 @@ public function actionInputHtml(): Response
             }
         }
 
-        $html = $this->getView()->renderTemplate('_components/fieldtypes/Categories/input',
+        $html = $this->getView()->renderTemplate('_components/fieldtypes/Categories/input.twig',
             [
                 'elements' => $categories,
                 'id' => $this->request->getParam('id'),
diff --git a/src/controllers/DashboardController.php b/src/controllers/DashboardController.php
index 4fa495d44f3..fc7cfbb1428 100644
--- a/src/controllers/DashboardController.php
+++ b/src/controllers/DashboardController.php
@@ -142,7 +142,7 @@ public function actionIndex(): Response
 
         $variables['widgetTypes'] = $widgetTypeInfo;
 
-        return $this->renderTemplate('dashboard/_index', $variables);
+        return $this->renderTemplate('dashboard/_index.twig', $variables);
     }
 
     /**
@@ -301,7 +301,7 @@ public function actionSendSupportRequest(): Response
         $getHelpModel->attachment = UploadedFile::getInstanceByName($namespace . 'attachAdditionalFile');
 
         if (!$getHelpModel->validate()) {
-            return $this->renderTemplate('_components/widgets/CraftSupport/response', [
+            return $this->renderTemplate('_components/widgets/CraftSupport/response.twig', [
                 'widgetId' => $widgetId,
                 'success' => false,
                 'errors' => $getHelpModel->getErrors(),
@@ -434,7 +434,7 @@ public function actionSendSupportRequest(): Response
         }
 
         if (isset($requestException)) {
-            return $this->renderTemplate('_components/widgets/CraftSupport/response', [
+            return $this->renderTemplate('_components/widgets/CraftSupport/response.twig', [
                 'widgetId' => $widgetId,
                 'success' => false,
                 'errors' => [
@@ -445,7 +445,7 @@ public function actionSendSupportRequest(): Response
             ]);
         }
 
-        return $this->renderTemplate('_components/widgets/CraftSupport/response', [
+        return $this->renderTemplate('_components/widgets/CraftSupport/response.twig', [
             'widgetId' => $widgetId,
             'success' => true,
             'errors' => [],
diff --git a/src/controllers/ElementIndexesController.php b/src/controllers/ElementIndexesController.php
index cc56a3f38bb..b64cff7eaef 100644
--- a/src/controllers/ElementIndexesController.php
+++ b/src/controllers/ElementIndexesController.php
@@ -294,7 +294,7 @@ public function actionGetSourceTreeHtml(): Response
         $sources = Craft::$app->getElementSources()->getSources($this->elementType, $this->context);
 
         return $this->asJson([
-            'html' => $this->getView()->renderTemplate('_elements/sources', [
+            'html' => $this->getView()->renderTemplate('_elements/sources.twig', [
                 'elementType' => $this->elementType,
                 'sources' => $sources,
             ]),
diff --git a/src/controllers/ElementSelectorModalsController.php b/src/controllers/ElementSelectorModalsController.php
index c3fd64bbde8..6abf6bcb577 100644
--- a/src/controllers/ElementSelectorModalsController.php
+++ b/src/controllers/ElementSelectorModalsController.php
@@ -99,7 +99,7 @@ public function actionBody(): Response
         })();
 
         return $this->asJson([
-            'html' => $this->getView()->renderTemplate('_elements/modalbody', [
+            'html' => $this->getView()->renderTemplate('_elements/modalbody.twig', [
                 'context' => $context,
                 'elementType' => $elementType,
                 'sources' => $sources,
diff --git a/src/controllers/ElementsController.php b/src/controllers/ElementsController.php
index af57bdf057f..c10bafca25c 100644
--- a/src/controllers/ElementsController.php
+++ b/src/controllers/ElementsController.php
@@ -616,7 +616,7 @@ private function _contextMenu(
             $showDrafts ||
             ($element->hasRevisions() && $element::find()->revisionOf($element)->status(null)->exists())
         ) {
-            return Craft::$app->getView()->renderTemplate('_includes/revisionmenu', [
+            return Craft::$app->getView()->renderTemplate('_includes/revisionmenu.twig', [
                 'element' => $element,
                 'showDrafts' => $showDrafts,
                 'supportedSiteIds' => $propSiteIds,
@@ -1187,7 +1187,7 @@ public function actionSaveDraft(): ?Response
             $tabs = $form->getTabMenu();
             if (count($tabs) > 1) {
                 $selectedTab = isset($tabs[$this->_selectedTab]) ? $this->_selectedTab : null;
-                $tabHtml = $view->namespaceInputs(fn() => $view->renderTemplate('_includes/tabs', [
+                $tabHtml = $view->namespaceInputs(fn() => $view->renderTemplate('_includes/tabs.twig', [
                     'tabs' => $tabs,
                     'selectedTab' => $selectedTab,
                 ], View::TEMPLATE_MODE_CP), $namespace);
diff --git a/src/controllers/EntriesController.php b/src/controllers/EntriesController.php
index 15e3da37fb5..29f3f4f53b3 100644
--- a/src/controllers/EntriesController.php
+++ b/src/controllers/EntriesController.php
@@ -78,7 +78,7 @@ public function actionCreate(?string $section = null): ?Response
         if (!in_array($site->id, $editableSiteIds)) {
             // If there’s more than one possibility and entries doesn’t propagate to all sites, let the user choose
             if (count($editableSiteIds) > 1 && $section->propagationMethod !== Section::PROPAGATION_METHOD_ALL) {
-                return $this->renderTemplate('_special/sitepicker', [
+                return $this->renderTemplate('_special/sitepicker.twig', [
                     'siteIds' => $editableSiteIds,
                     'baseUrl' => "entries/$section->handle/new",
                 ]);
diff --git a/src/controllers/FieldsController.php b/src/controllers/FieldsController.php
index d7cae016027..0587bdfd653 100644
--- a/src/controllers/FieldsController.php
+++ b/src/controllers/FieldsController.php
@@ -257,7 +257,7 @@ public function actionEditField(?int $fieldId = null, ?FieldInterface $field = n
         $view->registerAssetBundle(FieldSettingsAsset::class);
         $view->registerJs($js);
 
-        return $this->renderTemplate('settings/fields/_edit', compact(
+        return $this->renderTemplate('settings/fields/_edit.twig', compact(
             'fieldId',
             'field',
             'allFieldTypes',
@@ -287,7 +287,7 @@ public function actionRenderSettings(): Response
         $field = Craft::$app->getFields()->createField($type);
 
         $view = Craft::$app->getView();
-        $html = $view->renderTemplate('settings/fields/_type-settings', [
+        $html = $view->renderTemplate('settings/fields/_type-settings.twig', [
             'field' => $field,
             'namespace' => $this->request->getBodyParam('namespace'),
         ]);
diff --git a/src/controllers/FsController.php b/src/controllers/FsController.php
index c6fbaeaa0b9..671f09aca85 100644
--- a/src/controllers/FsController.php
+++ b/src/controllers/FsController.php
@@ -49,7 +49,7 @@ public function actionIndex(): Response
         $variables = [];
         $variables['filesystems'] = Craft::$app->getFs()->getAllFilesystems();
 
-        return $this->renderTemplate('settings/filesystems/_index', $variables);
+        return $this->renderTemplate('settings/filesystems/_index.twig', $variables);
     }
 
     /**
@@ -112,7 +112,7 @@ public function actionEdit(?string $handle = null, ?Fs $filesystem = null): Resp
             ->addCrumb(Craft::t('app', 'Filesystems'), 'settings/filesystems')
             ->action('fs/save')
             ->redirectUrl('settings/filesystems')
-            ->contentTemplate('settings/filesystems/_edit', [
+            ->contentTemplate('settings/filesystems/_edit.twig', [
                 'oldHandle' => $handle,
                 'filesystem' => $filesystem,
                 'fsOptions' => $fsOptions,
diff --git a/src/controllers/GlobalsController.php b/src/controllers/GlobalsController.php
index 7d75219b71c..9937f170de3 100644
--- a/src/controllers/GlobalsController.php
+++ b/src/controllers/GlobalsController.php
@@ -174,7 +174,7 @@ public function actionEditContent(string $globalSetHandle, ?GlobalSet $globalSet
         ]);
 
         // Render the template!
-        return $this->renderTemplate('globals/_edit', [
+        return $this->renderTemplate('globals/_edit.twig', [
             'bodyClass' => 'edit-global-set',
             'editableGlobalSets' => $editableGlobalSets,
             'globalSet' => $globalSet,
diff --git a/src/controllers/GraphqlController.php b/src/controllers/GraphqlController.php
index 139aab15273..ab77b12ed19 100644
--- a/src/controllers/GraphqlController.php
+++ b/src/controllers/GraphqlController.php
@@ -319,7 +319,7 @@ public function actionGraphiql(): Response
             $schemas[$name] = $schema->uid;
         }
 
-        return $this->renderTemplate('graphql/graphiql', [
+        return $this->renderTemplate('graphql/graphiql.twig', [
             'url' => UrlHelper::actionUrl('graphql/api'),
             'schemas' => $schemas,
             'selectedSchema' => $selectedSchema,
@@ -362,7 +362,7 @@ public function actionViewSchemas(): Response
         // Ensure the public schema is created.
         Craft::$app->getGql()->getPublicSchema();
 
-        return $this->renderTemplate('graphql/schemas/_index');
+        return $this->renderTemplate('graphql/schemas/_index.twig');
     }
 
     /**
@@ -419,7 +419,7 @@ public function actionEditToken(?int $tokenId = null, ?GqlToken $token = null):
             ]);
         }
 
-        return $this->renderTemplate('graphql/tokens/_edit', compact(
+        return $this->renderTemplate('graphql/tokens/_edit.twig', compact(
             'token',
             'title',
             'accessToken',
@@ -503,7 +503,7 @@ public function actionDeleteToken(): Response
     public function actionViewTokens(): Response
     {
         $this->requireAdmin(false);
-        return $this->renderTemplate('graphql/tokens/_index');
+        return $this->renderTemplate('graphql/tokens/_index.twig');
     }
 
     /**
@@ -536,7 +536,7 @@ public function actionEditSchema(?int $schemaId = null, ?GqlSchema $schema = nul
         }
 
 
-        return $this->renderTemplate('graphql/schemas/_edit', compact(
+        return $this->renderTemplate('graphql/schemas/_edit.twig', compact(
             'schema',
             'title'
         ));
@@ -562,7 +562,7 @@ public function actionEditPublicSchema(?GqlSchema $schema = null): Response
         $token = $gqlService->getPublicToken();
         $title = Craft::t('app', 'Edit the public GraphQL schema');
 
-        return $this->renderTemplate('graphql/schemas/_edit', compact(
+        return $this->renderTemplate('graphql/schemas/_edit.twig', compact(
             'schema',
             'token',
             'title'
diff --git a/src/controllers/ImageTransformsController.php b/src/controllers/ImageTransformsController.php
index 5d991f2509c..2ada6670638 100644
--- a/src/controllers/ImageTransformsController.php
+++ b/src/controllers/ImageTransformsController.php
@@ -48,7 +48,7 @@ public function actionIndex(): Response
         $variables['transforms'] = Craft::$app->getImageTransforms()->getAllTransforms();
         $variables['modes'] = ImageTransform::modes();
 
-        return $this->renderTemplate('settings/assets/transforms/_index', $variables);
+        return $this->renderTemplate('settings/assets/transforms/_index.twig', $variables);
     }
 
     /**
@@ -81,7 +81,7 @@ public function actionEdit(?string $transformHandle = null, ?ImageTransform $tra
             $title = Craft::t('app', 'Create a new image transform');
         }
 
-        return $this->renderTemplate('settings/assets/transforms/_settings', [
+        return $this->renderTemplate('settings/assets/transforms/_settings.twig', [
             'handle' => $transformHandle,
             'transform' => $transform,
             'title' => $title,
diff --git a/src/controllers/InstallController.php b/src/controllers/InstallController.php
index aaee7268988..6d8043ac5b2 100644
--- a/src/controllers/InstallController.php
+++ b/src/controllers/InstallController.php
@@ -99,7 +99,7 @@ public function actionIndex(): Response
         $userIcon = file_get_contents($iconsPath . DIRECTORY_SEPARATOR . 'user.svg');
         $worldIcon = file_get_contents($iconsPath . DIRECTORY_SEPARATOR . 'world.svg');
 
-        return $this->renderTemplate('_special/install', compact(
+        return $this->renderTemplate('_special/install/index.twig', compact(
             'showDbScreen',
             'license',
             'defaultSystemName',
diff --git a/src/controllers/PluginStoreController.php b/src/controllers/PluginStoreController.php
index 40331c348bd..8a00fac76a9 100644
--- a/src/controllers/PluginStoreController.php
+++ b/src/controllers/PluginStoreController.php
@@ -79,7 +79,7 @@ public function actionIndex(): Response
 
         $view->registerAssetBundle(PluginStoreAsset::class);
 
-        return $this->renderTemplate('plugin-store/_index');
+        return $this->renderTemplate('plugin-store/_index.twig');
     }
 
     /**
@@ -170,7 +170,7 @@ public function actionCallback(): Response
 
         $this->getView()->registerJs('new Craft.PluginStoreOauthCallback(' . Json::encode($options) . ');');
 
-        return $this->renderTemplate('plugin-store/_special/oauth/callback');
+        return $this->renderTemplate('plugin-store/_special/oauth/callback.twig');
     }
 
     /**
@@ -182,7 +182,7 @@ public function actionModalCallback(): Response
     {
         $craftIdAccessToken = $this->getCraftIdAccessToken();
 
-        return $this->renderTemplate('plugin-store/_special/oauth/modal-callback', [
+        return $this->renderTemplate('plugin-store/_special/oauth/modal-callback.twig', [
             'craftIdAccessToken' => $craftIdAccessToken,
         ]);
     }
diff --git a/src/controllers/RebrandController.php b/src/controllers/RebrandController.php
index cc0e54b4a1c..b3e4c150fa2 100644
--- a/src/controllers/RebrandController.php
+++ b/src/controllers/RebrandController.php
@@ -84,7 +84,7 @@ public function actionUploadSiteImage(): Response
         }
 
         $imagesService->loadImage($fileDestination)->scaleToFit(300, 300)->saveAs($fileDestination);
-        $html = $this->getView()->renderTemplate('settings/general/_images/' . $type);
+        $html = $this->getView()->renderTemplate("settings/general/_images/$type.twig");
 
         return $this->asJson([
             'html' => $html,
@@ -107,7 +107,7 @@ public function actionDeleteSiteImage(): ?Response
 
         FileHelper::clearDirectory(Craft::$app->getPath()->getRebrandPath() . '/' . $type);
 
-        $html = $this->getView()->renderTemplate('settings/general/_images/' . $type);
+        $html = $this->getView()->renderTemplate("settings/general/_images/$type.twig");
 
         return $this->asJson([
             'html' => $html,
diff --git a/src/controllers/SectionsController.php b/src/controllers/SectionsController.php
index d302c25e671..94867b8a7f3 100644
--- a/src/controllers/SectionsController.php
+++ b/src/controllers/SectionsController.php
@@ -52,7 +52,7 @@ public function actionIndex(array $variables = []): Response
     {
         $variables['sections'] = Craft::$app->getSections()->getAllSections();
 
-        return $this->renderTemplate('settings/sections/_index', $variables);
+        return $this->renderTemplate('settings/sections/_index.twig', $variables);
     }
 
     /**
@@ -105,7 +105,7 @@ public function actionEditSection(?int $sectionId = null, ?Section $section = nu
 
         $this->getView()->registerAssetBundle(EditSectionAsset::class);
 
-        return $this->renderTemplate('settings/sections/_edit', $variables);
+        return $this->renderTemplate('settings/sections/_edit.twig', $variables);
     }
 
     /**
@@ -225,7 +225,7 @@ public function actionEntryTypesIndex(int $sectionId): Response
         $title = Craft::t('app', '{section} Entry Types',
             ['section' => Craft::t('site', $section->name)]);
 
-        return $this->renderTemplate('settings/sections/_entrytypes/index', [
+        return $this->renderTemplate('settings/sections/_entrytypes/index.twig', [
             'sectionId' => $sectionId,
             'section' => $section,
             'title' => $title,
@@ -293,7 +293,7 @@ public function actionEditEntryType(int $sectionId, ?int $entryTypeId = null, ?E
             ],
         ];
 
-        return $this->renderTemplate('settings/sections/_entrytypes/edit', [
+        return $this->renderTemplate('settings/sections/_entrytypes/edit.twig', [
             'sectionId' => $sectionId,
             'section' => $section,
             'entryTypeId' => $entryTypeId,
diff --git a/src/controllers/SitesController.php b/src/controllers/SitesController.php
index 66b22ffe9ea..2e726971845 100644
--- a/src/controllers/SitesController.php
+++ b/src/controllers/SitesController.php
@@ -82,7 +82,7 @@ public function actionSettingsIndex(?int $groupId = null): Response
             'Delete {site}',
         ]);
 
-        return $this->renderTemplate('settings/sites/index', compact(
+        return $this->renderTemplate('settings/sites/index.twig', compact(
             'crumbs',
             'allGroups',
             'group',
@@ -278,7 +278,7 @@ public function actionEditSite(?int $siteId = null, ?Site $siteModel = null, ?in
             ];
         }
 
-        return $this->renderTemplate('settings/sites/_edit', [
+        return $this->renderTemplate('settings/sites/_edit.twig', [
             'brandNewSite' => $brandNewSite,
             'title' => $title,
             'crumbs' => $crumbs,
diff --git a/src/controllers/SystemMessagesController.php b/src/controllers/SystemMessagesController.php
index 629f153f9b9..6548e77f10f 100644
--- a/src/controllers/SystemMessagesController.php
+++ b/src/controllers/SystemMessagesController.php
@@ -54,7 +54,7 @@ public function actionGetMessageModal(): Response
         $message = Craft::$app->getSystemMessages()->getMessage($key, $language);
 
         return $this->asJson([
-            'body' => $this->getView()->renderTemplate('_components/utilities/SystemMessages/message-modal', [
+            'body' => $this->getView()->renderTemplate('_components/utilities/SystemMessages/message-modal.twig', [
                 'message' => $message,
                 'language' => $language,
             ]),
diff --git a/src/controllers/SystemSettingsController.php b/src/controllers/SystemSettingsController.php
index 88e61ebe7f3..6b00a5e7dd9 100644
--- a/src/controllers/SystemSettingsController.php
+++ b/src/controllers/SystemSettingsController.php
@@ -55,7 +55,7 @@ public function actionGeneralSettings(): Response
     {
         $this->getView()->registerAssetBundle(GeneralSettingsAsset::class);
 
-        return $this->renderTemplate('settings/general/_index', [
+        return $this->renderTemplate('settings/general/_index.twig', [
             'system' => Craft::$app->getProjectConfig()->get('system') ?? [],
         ]);
     }
@@ -147,7 +147,7 @@ public function actionEditEmailSettings(?MailSettings $settings = null, ?Transpo
             }
         }
 
-        return $this->renderTemplate('settings/email/_index', [
+        return $this->renderTemplate('settings/email/_index.twig', [
             'settings' => $settings,
             'adapter' => $adapter,
             'transportTypeOptions' => $transportTypeOptions,
@@ -271,7 +271,7 @@ public function actionEditGlobalSet(?int $globalSetId = null, ?GlobalSet $global
         ];
 
         // Render the template!
-        return $this->renderTemplate('settings/globals/_edit', [
+        return $this->renderTemplate('settings/globals/_edit.twig', [
             'globalSetId' => $globalSetId,
             'globalSet' => $globalSet,
             'title' => $title,
diff --git a/src/controllers/TagsController.php b/src/controllers/TagsController.php
index a3a513712c4..9f442e4e087 100644
--- a/src/controllers/TagsController.php
+++ b/src/controllers/TagsController.php
@@ -40,7 +40,7 @@ public function actionIndex(): Response
 
         $tagGroups = Craft::$app->getTags()->getAllTagGroups();
 
-        return $this->renderTemplate('settings/tags/index', [
+        return $this->renderTemplate('settings/tags/index.twig', [
             'tagGroups' => $tagGroups,
         ]);
     }
@@ -87,7 +87,7 @@ public function actionEditTagGroup(?int $tagGroupId = null, ?TagGroup $tagGroup
             ],
         ];
 
-        return $this->renderTemplate('settings/tags/_edit', [
+        return $this->renderTemplate('settings/tags/_edit.twig', [
             'tagGroupId' => $tagGroupId,
             'tagGroup' => $tagGroup,
             'title' => $title,
diff --git a/src/controllers/TemplatesController.php b/src/controllers/TemplatesController.php
index b848bd5b828..1e21f33aebe 100644
--- a/src/controllers/TemplatesController.php
+++ b/src/controllers/TemplatesController.php
@@ -130,7 +130,7 @@ public function actionOffline(): Response
      */
     public function actionManualUpdateNotification(): Response
     {
-        return $this->renderTemplate('_special/dbupdate');
+        return $this->renderTemplate('_special/dbupdate.twig');
     }
 
     /**
@@ -163,7 +163,7 @@ public function actionRequirementsCheck(): ?Response
                 throw new ServerErrorHttpException(Craft::t('app', 'The update can’t be installed :( {message}', ['message' => $message]));
             }
 
-            return $this->renderTemplate('_special/cantrun', [
+            return $this->renderTemplate('_special/cantrun.twig', [
                 'reqCheck' => $reqCheck,
             ]);
         }
diff --git a/src/controllers/UsersController.php b/src/controllers/UsersController.php
index 019083a9879..8cb1ee1a732 100644
--- a/src/controllers/UsersController.php
+++ b/src/controllers/UsersController.php
@@ -670,7 +670,7 @@ public function actionVerifyEmail(): Response
         // Do they have an unverified email?
         if ($user->unverifiedEmail) {
             if (!$usersService->verifyEmailForUser($user)) {
-                return $this->renderTemplate('_special/emailtaken', [
+                return $this->renderTemplate('_special/emailtaken.twig', [
                     'email' => $user->unverifiedEmail,
                 ]);
             }
@@ -1092,7 +1092,7 @@ public function actionEditUser(mixed $userId = null, ?User $user = null, ?array
             View::POS_END
         );
 
-        return $this->renderTemplate('users/_edit', compact(
+        return $this->renderTemplate('users/_edit.twig', compact(
             'user',
             'isNewUser',
             'statusLabel',
@@ -2092,7 +2092,7 @@ private function _renderSetPasswordTemplate(array $variables): Response
         }
 
         // Otherwise go with the control panel’s template
-        return $this->renderTemplate('setpassword', $variables, View::TEMPLATE_MODE_CP);
+        return $this->renderTemplate('setpassword.twig', $variables, View::TEMPLATE_MODE_CP);
     }
 
     /**
@@ -2496,7 +2496,7 @@ private function _renderPhotoTemplate(User $user): string
             $templateMode = View::TEMPLATE_MODE_CP;
         }
 
-        return $view->renderTemplate('users/_photo', [
+        return $view->renderTemplate('users/_photo.twig', [
             'user' => $user,
         ], $templateMode);
     }
diff --git a/src/controllers/UtilitiesController.php b/src/controllers/UtilitiesController.php
index 4f414d0055c..04787ff2c74 100644
--- a/src/controllers/UtilitiesController.php
+++ b/src/controllers/UtilitiesController.php
@@ -84,7 +84,7 @@ public function actionShowUtility(string $id): Response
 
         $this->getView()->registerAssetBundle(UtilitiesAsset::class);
 
-        return $this->renderTemplate('utilities/_index', [
+        return $this->renderTemplate('utilities/_index.twig', [
             'id' => $id,
             'displayName' => $class::displayName(),
             'contentHtml' => $class::contentHtml(),
@@ -107,7 +107,7 @@ public function actionGetDeprecationErrorTracesModal(): Response
         $this->requireAcceptsJson();
 
         $logId = Craft::$app->request->getRequiredParam('logId');
-        $html = $this->getView()->renderTemplate('_components/utilities/DeprecationErrors/traces_modal', [
+        $html = $this->getView()->renderTemplate('_components/utilities/DeprecationErrors/traces_modal.twig', [
             'log' => Craft::$app->deprecator->getLogById($logId),
         ]);
 
diff --git a/src/controllers/VolumesController.php b/src/controllers/VolumesController.php
index 5f84f3ee4f9..9821098aee8 100644
--- a/src/controllers/VolumesController.php
+++ b/src/controllers/VolumesController.php
@@ -51,7 +51,7 @@ public function actionVolumeIndex(): Response
         $variables = [];
         $variables['volumes'] = Craft::$app->getVolumes()->getAllVolumes();
 
-        return $this->renderTemplate('settings/assets/volumes/_index', $variables);
+        return $this->renderTemplate('settings/assets/volumes/_index.twig', $variables);
     }
 
     /**
@@ -118,7 +118,7 @@ public function actionEditVolume(?int $volumeId = null, ?Volume $volume = null):
             ->redirectUrl('settings/assets')
             ->saveShortcutRedirectUrl('settings/assets/volumes/{id}')
             ->editUrl($volume->id ? "settings/assets/volumes/$volume->id" : null)
-            ->contentTemplate('settings/assets/volumes/_edit', [
+            ->contentTemplate('settings/assets/volumes/_edit.twig', [
                 'volumeId' => $volumeId,
                 'volume' => $volume,
                 'isNewVolume' => $isNewVolume,
diff --git a/src/elements/User.php b/src/elements/User.php
index 31e8805483a..7b68b2ded2b 100644
--- a/src/elements/User.php
+++ b/src/elements/User.php
@@ -1606,7 +1606,7 @@ protected function htmlAttributes(string $context): array
     protected function metaFieldsHtml(bool $static): string
     {
         return implode("\n", [
-            Craft::$app->getView()->renderTemplate('users/_accountfields', [
+            Craft::$app->getView()->renderTemplate('users/_accountfields.twig', [
                 'user' => $this,
                 'isNewUser' => !$this->id,
                 'static' => $static,
diff --git a/src/elements/actions/SetStatus.php b/src/elements/actions/SetStatus.php
index 39d50a9e1c7..a533efc76e9 100644
--- a/src/elements/actions/SetStatus.php
+++ b/src/elements/actions/SetStatus.php
@@ -65,7 +65,7 @@ public function getTriggerHtml(): ?string
 })();
 JS, [static::class]);
 
-        return Craft::$app->getView()->renderTemplate('_components/elementactions/SetStatus/trigger');
+        return Craft::$app->getView()->renderTemplate('_components/elementactions/SetStatus/trigger.twig');
     }
 
     /**
diff --git a/src/fieldlayoutelements/BaseField.php b/src/fieldlayoutelements/BaseField.php
index ec2772a144a..6680059cb07 100644
--- a/src/fieldlayoutelements/BaseField.php
+++ b/src/fieldlayoutelements/BaseField.php
@@ -199,7 +199,7 @@ public function hasCustomWidth(): bool
      */
     protected function settingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_includes/forms/fld/field-settings', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/fld/field-settings.twig', [
             'field' => $this,
             'defaultLabel' => $this->defaultLabel(),
             'defaultInstructions' => $this->defaultInstructions(),
diff --git a/src/fieldlayoutelements/TextField.php b/src/fieldlayoutelements/TextField.php
index c6b356c8924..de366d9e75c 100644
--- a/src/fieldlayoutelements/TextField.php
+++ b/src/fieldlayoutelements/TextField.php
@@ -122,7 +122,7 @@ public function fields(): array
      */
     protected function inputHtml(?ElementInterface $element = null, bool $static = false): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_includes/forms/text', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/text.twig', [
             'type' => $this->type,
             'autocomplete' => $this->autocomplete,
             'class' => $this->class,
diff --git a/src/fieldlayoutelements/TextareaField.php b/src/fieldlayoutelements/TextareaField.php
index 3bb3742d724..093d23b3216 100644
--- a/src/fieldlayoutelements/TextareaField.php
+++ b/src/fieldlayoutelements/TextareaField.php
@@ -88,7 +88,7 @@ public function fields(): array
      */
     protected function inputHtml(?ElementInterface $element = null, bool $static = false): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_includes/forms/textarea', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/textarea.twig', [
             'class' => $this->class,
             'id' => $this->id(),
             'describedBy' => $this->describedBy($element, $static),
diff --git a/src/fields/Assets.php b/src/fields/Assets.php
index 00d25709331..6f7ba738d49 100644
--- a/src/fields/Assets.php
+++ b/src/fields/Assets.php
@@ -180,12 +180,12 @@ public static function valueType(): string
     /**
      * @inheritdoc
      */
-    protected string $settingsTemplate = '_components/fieldtypes/Assets/settings';
+    protected string $settingsTemplate = '_components/fieldtypes/Assets/settings.twig';
 
     /**
      * @inheritdoc
      */
-    protected string $inputTemplate = '_components/fieldtypes/Assets/input';
+    protected string $inputTemplate = '_components/fieldtypes/Assets/input.twig';
 
     /**
      * @inheritdoc
diff --git a/src/fields/BaseRelationField.php b/src/fields/BaseRelationField.php
index e529009885b..7ab2f582bc7 100644
--- a/src/fields/BaseRelationField.php
+++ b/src/fields/BaseRelationField.php
@@ -191,12 +191,12 @@ public static function valueType(): string
     /**
      * @var string Template to use for settings rendering
      */
-    protected string $settingsTemplate = '_components/fieldtypes/elementfieldsettings';
+    protected string $settingsTemplate = '_components/fieldtypes/elementfieldsettings.twig';
 
     /**
      * @var string Template to use for field rendering
      */
-    protected string $inputTemplate = '_includes/forms/elementSelect';
+    protected string $inputTemplate = '_includes/forms/elementSelect.twig';
 
     /**
      * @var string|null The JS class that should be initialized for the input
diff --git a/src/fields/Categories.php b/src/fields/Categories.php
index 659a3ffb96d..23ef95e47cd 100644
--- a/src/fields/Categories.php
+++ b/src/fields/Categories.php
@@ -82,12 +82,12 @@ public static function valueType(): string
     /**
      * @inheritdoc
      */
-    protected string $settingsTemplate = '_components/fieldtypes/Categories/settings';
+    protected string $settingsTemplate = '_components/fieldtypes/Categories/settings.twig';
 
     /**
      * @inheritdoc
      */
-    protected string $inputTemplate = '_components/fieldtypes/Categories/input';
+    protected string $inputTemplate = '_components/fieldtypes/Categories/input.twig';
 
     /**
      * @inheritdoc
diff --git a/src/fields/Checkboxes.php b/src/fields/Checkboxes.php
index 4a5cd54c736..68465b2a836 100644
--- a/src/fields/Checkboxes.php
+++ b/src/fields/Checkboxes.php
@@ -59,7 +59,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             Craft::$app->getView()->setInitialDeltaValue($this->handle, null);
         }
 
-        return Craft::$app->getView()->renderTemplate('_includes/forms/checkboxGroup', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/checkboxGroup.twig', [
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
             'values' => $this->encodeValue($value),
diff --git a/src/fields/Color.php b/src/fields/Color.php
index 8bdf4b20f67..0fa6279a519 100644
--- a/src/fields/Color.php
+++ b/src/fields/Color.php
@@ -124,7 +124,7 @@ public function getElementValidationRules(): array
     protected function inputHtml(mixed $value, ?ElementInterface $element = null): string
     {
         /** @var ColorData|null $value */
-        return Craft::$app->getView()->renderTemplate('_includes/forms/color', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/color.twig', [
             'id' => $this->getInputId(),
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
diff --git a/src/fields/Date.php b/src/fields/Date.php
index 85ad3cb79cf..12c92b74668 100644
--- a/src/fields/Date.php
+++ b/src/fields/Date.php
@@ -215,7 +215,7 @@ public function getSettingsHtml(): ?string
             'value' => 'showBoth',
         ];
 
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Date/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Date/settings.twig', [
             'options' => $options,
             'value' => $dateTimeValue,
             'incrementOptions' => $incrementOptions,
@@ -267,15 +267,15 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
         ];
 
         if ($this->showDate) {
-            $components[] = $view->renderTemplate('_includes/forms/date', $variables);
+            $components[] = $view->renderTemplate('_includes/forms/date.twig', $variables);
         }
 
         if ($this->showTime) {
-            $components[] = $view->renderTemplate('_includes/forms/time', $variables);
+            $components[] = $view->renderTemplate('_includes/forms/time.twig', $variables);
         }
 
         if ($this->showTimeZone) {
-            $components[] = $view->renderTemplate('_includes/forms/timeZone', [
+            $components[] = $view->renderTemplate('_includes/forms/timeZone.twig', [
                 'describedBy' => $this->describedBy,
                 'name' => "$this->handle[timezone]",
                 'value' => $timezone,
diff --git a/src/fields/Dropdown.php b/src/fields/Dropdown.php
index 71b22f33a6f..79acef0329b 100644
--- a/src/fields/Dropdown.php
+++ b/src/fields/Dropdown.php
@@ -62,7 +62,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             }
         }
 
-        return Craft::$app->getView()->renderTemplate('_includes/forms/select', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/select.twig', [
             'id' => $this->getInputId(),
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
diff --git a/src/fields/Email.php b/src/fields/Email.php
index 42816a40481..30c2004020b 100644
--- a/src/fields/Email.php
+++ b/src/fields/Email.php
@@ -102,7 +102,7 @@ public function serializeValue(mixed $value, ElementInterface $element = null):
      */
     protected function inputHtml(mixed $value, ?ElementInterface $element = null): string
     {
-        return Craft::$app->getView()->renderTemplate('_includes/forms/text', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/text.twig', [
             'type' => 'email',
             'id' => $this->getInputId(),
             'describedBy' => $this->describedBy,
diff --git a/src/fields/Lightswitch.php b/src/fields/Lightswitch.php
index d2a48276ee8..72085a87930 100644
--- a/src/fields/Lightswitch.php
+++ b/src/fields/Lightswitch.php
@@ -126,7 +126,7 @@ public function getSettingsHtml(): ?string
     protected function inputHtml(mixed $value, ?ElementInterface $element = null): string
     {
         $id = $this->getInputId();
-        return Craft::$app->getView()->renderTemplate('_includes/forms/lightswitch', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/lightswitch.twig', [
             'id' => $id,
             'labelId' => $this->getLabelId(),
             'describedBy' => $this->describedBy,
diff --git a/src/fields/Matrix.php b/src/fields/Matrix.php
index 3522133392a..793109eb832 100644
--- a/src/fields/Matrix.php
+++ b/src/fields/Matrix.php
@@ -480,7 +480,7 @@ public function getSettingsHtml(): ?string
             }
         }
 
-        return $view->renderTemplate('_components/fieldtypes/Matrix/settings',
+        return $view->renderTemplate('_components/fieldtypes/Matrix/settings.twig',
             [
                 'matrixField' => $this,
                 'fieldTypes' => $fieldTypeOptions,
@@ -735,7 +735,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
 
         $view->registerJs($js);
 
-        return $view->renderTemplate('_components/fieldtypes/Matrix/input',
+        return $view->renderTemplate('_components/fieldtypes/Matrix/input.twig',
             [
                 'id' => $id,
                 'name' => $this->handle,
@@ -863,7 +863,7 @@ public function getStaticHtml(mixed $value, ElementInterface $element): string
 
         $id = StringHelper::randomString();
 
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Matrix/input', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Matrix/input.twig', [
             'id' => $id,
             'name' => $id,
             'blockTypes' => $this->getBlockTypes(),
diff --git a/src/fields/Money.php b/src/fields/Money.php
index 7047d8b92d3..187c7c1f7ae 100644
--- a/src/fields/Money.php
+++ b/src/fields/Money.php
@@ -143,7 +143,7 @@ public function getSettingsHtml(): ?string
             }
         }
 
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Money/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Money/settings.twig', [
             'field' => $this,
             'currencies' => $this->_isoCurrencies,
             'subUnits' => $this->_isoCurrencies->subunitFor(new Currency($this->currency)),
@@ -298,7 +298,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             'currencySymbol' => Craft::$app->getFormattingLocale()->getCurrencySymbol($this->currency),
         ]);
 
-        return $view->renderTemplate('_components/fieldtypes/Money/input', [
+        return $view->renderTemplate('_components/fieldtypes/Money/input.twig', [
             'id' => $id,
             'currency' => $this->currency,
             'currencyLabel' => $currencyLabel,
diff --git a/src/fields/MultiSelect.php b/src/fields/MultiSelect.php
index e135b58d4d3..b2a90c1197f 100644
--- a/src/fields/MultiSelect.php
+++ b/src/fields/MultiSelect.php
@@ -56,7 +56,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             Craft::$app->getView()->setInitialDeltaValue($this->handle, null);
         }
 
-        return Craft::$app->getView()->renderTemplate('_includes/forms/multiselect', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/multiselect.twig', [
             'id' => $this->getInputId(),
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
diff --git a/src/fields/Number.php b/src/fields/Number.php
index 1d346381668..d2802d41057 100644
--- a/src/fields/Number.php
+++ b/src/fields/Number.php
@@ -157,7 +157,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Number/settings',
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Number/settings.twig',
             [
                 'field' => $this,
             ]);
@@ -281,7 +281,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
 
         $view->registerJs($js);
 
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Number/input', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Number/input.twig', [
             'id' => $id,
             'describedBy' => $this->describedBy,
             'field' => $this,
diff --git a/src/fields/PlainText.php b/src/fields/PlainText.php
index 73233604dd2..a9e84734ca8 100644
--- a/src/fields/PlainText.php
+++ b/src/fields/PlainText.php
@@ -166,7 +166,7 @@ public function validateFieldLimit(string $attribute): void
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/PlainText/settings',
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/PlainText/settings.twig',
             [
                 'field' => $this,
             ]);
@@ -210,7 +210,7 @@ public function normalizeValue(mixed $value, ?ElementInterface $element = null):
      */
     protected function inputHtml(mixed $value, ?ElementInterface $element = null): string
     {
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/PlainText/input', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/PlainText/input.twig', [
             'name' => $this->handle,
             'value' => $value,
             'field' => $this,
diff --git a/src/fields/RadioButtons.php b/src/fields/RadioButtons.php
index 4a3cf3aa58e..5d7f6553973 100644
--- a/src/fields/RadioButtons.php
+++ b/src/fields/RadioButtons.php
@@ -54,7 +54,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             Craft::$app->getView()->setInitialDeltaValue($this->handle, null);
         }
 
-        return Craft::$app->getView()->renderTemplate('_includes/forms/radioGroup', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/radioGroup.twig', [
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
             'value' => $this->encodeValue($value),
diff --git a/src/fields/Table.php b/src/fields/Table.php
index de48c36a2a4..47be4698575 100644
--- a/src/fields/Table.php
+++ b/src/fields/Table.php
@@ -319,7 +319,7 @@ public function getSettingsHtml(): ?string
             Json::encode($dropdownSettingsCols, JSON_UNESCAPED_UNICODE) .
             ');');
 
-        $columnsField = $view->renderTemplate('_components/fieldtypes/Table/columntable', [
+        $columnsField = $view->renderTemplate('_components/fieldtypes/Table/columntable.twig', [
             'cols' => $columnSettings,
             'rows' => $this->columns,
             'errors' => $this->getErrors('columns'),
@@ -338,7 +338,7 @@ public function getSettingsHtml(): ?string
             'initJs' => false,
         ]);
 
-        return $view->renderTemplate('_components/fieldtypes/Table/settings', [
+        return $view->renderTemplate('_components/fieldtypes/Table/settings.twig', [
             'field' => $this,
             'columnsField' => $columnsField,
             'defaultsField' => $defaultsField,
@@ -653,7 +653,7 @@ private function _getInputHtml(mixed $value, ?ElementInterface $element, bool $s
             }
         }
 
-        return Craft::$app->getView()->renderTemplate('_includes/forms/editableTable', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/editableTable.twig', [
             'id' => $this->getInputId(),
             'name' => $this->handle,
             'cols' => $this->columns,
diff --git a/src/fields/Tags.php b/src/fields/Tags.php
index 25b4da44444..fa259edcc79 100644
--- a/src/fields/Tags.php
+++ b/src/fields/Tags.php
@@ -98,7 +98,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
         $tagGroup = $this->_getTagGroup();
 
         if ($tagGroup) {
-            return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Tags/input',
+            return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Tags/input.twig',
                 [
                     'elementType' => static::elementType(),
                     'id' => $this->getInputId(),
diff --git a/src/fields/Time.php b/src/fields/Time.php
index fc5d17a2520..8a7eaedd967 100644
--- a/src/fields/Time.php
+++ b/src/fields/Time.php
@@ -116,7 +116,7 @@ public function getSettingsHtml(): ?string
         $incrementOptions = [5, 10, 15, 30, 60];
         $incrementOptions = array_combine($incrementOptions, $incrementOptions);
 
-        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Time/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/fieldtypes/Time/settings.twig', [
             'incrementOptions' => $incrementOptions,
             'field' => $this,
             'min' => $this->min ? DateTimeHelper::toDateTime(['time' => $this->min], true) : null,
@@ -137,7 +137,7 @@ public function getInputId(): string
      */
     protected function inputHtml(mixed $value, ?ElementInterface $element = null): string
     {
-        return Craft::$app->getView()->renderTemplate('_includes/forms/time', [
+        return Craft::$app->getView()->renderTemplate('_includes/forms/time.twig', [
             'id' => parent::getInputId(), // can't use $this->getInputId() here because the template adds the "-time"
             'describedBy' => $this->describedBy,
             'name' => $this->handle,
diff --git a/src/fields/Url.php b/src/fields/Url.php
index 7aeaca66531..e43eb036981 100644
--- a/src/fields/Url.php
+++ b/src/fields/Url.php
@@ -233,7 +233,7 @@ protected function inputHtml(mixed $value, ?ElementInterface $element = null): s
             }
         }
 
-        $input = Craft::$app->getView()->renderTemplate('_includes/forms/text', [
+        $input = Craft::$app->getView()->renderTemplate('_includes/forms/text.twig', [
             'id' => $id,
             'describedBy' => $this->describedBy,
             'class' => ['flex-grow', 'fullwidth'],
diff --git a/src/fs/Local.php b/src/fs/Local.php
index adeac618570..d0b59945b63 100644
--- a/src/fs/Local.php
+++ b/src/fs/Local.php
@@ -114,7 +114,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/fs/Local/settings',
+        return Craft::$app->getView()->renderTemplate('_components/fs/Local/settings.twig',
             [
                 'volume' => $this,
             ]);
diff --git a/src/helpers/Cp.php b/src/helpers/Cp.php
index 89baaffa331..55bf69f45cd 100644
--- a/src/helpers/Cp.php
+++ b/src/helpers/Cp.php
@@ -684,7 +684,7 @@ public static function fieldHtml(string $input, array $config = []): string
                     ($showAttribute
                         ? Html::tag('div', '', [
                             'class' => ['flex-grow'],
-                        ]) . static::renderTemplate('_includes/forms/copytextbtn', [
+                        ]) . static::renderTemplate('_includes/forms/copytextbtn.twig', [
                             'id' => "$id-attribute",
                             'class' => ['code', 'small', 'light'],
                             'value' => $config['attribute'],
@@ -709,7 +709,7 @@ public static function fieldHtml(string $input, array $config = []): string
             self::_noticeHtml($tipId, 'notice', Craft::t('app', 'Tip:'), $tip) .
             self::_noticeHtml($warningId, 'warning', Craft::t('app', 'Warning:'), $warning) .
             ($errors
-                ? static::renderTemplate('_includes/forms/errorList', [
+                ? static::renderTemplate('_includes/forms/errorList.twig', [
                     'id' => $errorsId,
                     'errors' => $errors,
                 ])
@@ -772,7 +772,7 @@ public static function checkboxFieldHtml(array $config): string
         // Don't pass along `label` since it's ambiguous
         unset($config['label']);
 
-        return static::fieldHtml('template:_includes/forms/checkbox', $config);
+        return static::fieldHtml('template:_includes/forms/checkbox.twig', $config);
     }
 
     /**
@@ -787,7 +787,7 @@ public static function checkboxSelectFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'checkboxselect' . mt_rand();
         $config['fieldset'] = true;
-        return static::fieldHtml('template:_includes/forms/checkboxSelect', $config);
+        return static::fieldHtml('template:_includes/forms/checkboxSelect.twig', $config);
     }
 
     /**
@@ -802,7 +802,7 @@ public static function colorFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'color' . mt_rand();
         $config['fieldset'] = true;
-        return static::fieldHtml('template:_includes/forms/color', $config);
+        return static::fieldHtml('template:_includes/forms/color.twig', $config);
     }
 
     /**
@@ -816,7 +816,7 @@ public static function colorFieldHtml(array $config): string
     public static function editableTableFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'editabletable' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/editableTable', $config);
+        return static::fieldHtml('template:_includes/forms/editableTable.twig', $config);
     }
 
     /**
@@ -829,7 +829,7 @@ public static function editableTableFieldHtml(array $config): string
      */
     public static function lightswitchHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/lightswitch', $config);
+        return static::renderTemplate('_includes/forms/lightswitch.twig', $config);
     }
 
     /**
@@ -851,7 +851,7 @@ public static function lightswitchFieldHtml(array $config): string
         $config['fieldLabel'] = $config['fieldLabel'] ?? $config['label'] ?? null;
         unset($config['label']);
 
-        return static::fieldHtml('template:_includes/forms/lightswitch', $config);
+        return static::fieldHtml('template:_includes/forms/lightswitch.twig', $config);
     }
 
     /**
@@ -863,7 +863,7 @@ public static function lightswitchFieldHtml(array $config): string
      */
     public static function selectHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/select', $config);
+        return static::renderTemplate('_includes/forms/select.twig', $config);
     }
 
     /**
@@ -877,7 +877,7 @@ public static function selectHtml(array $config): string
     public static function selectFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'select' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/select', $config);
+        return static::fieldHtml('template:_includes/forms/select.twig', $config);
     }
 
     /**
@@ -889,7 +889,7 @@ public static function selectFieldHtml(array $config): string
      */
     public static function selectizeHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/selectize', $config);
+        return static::renderTemplate('_includes/forms/selectize.twig', $config);
     }
 
     /**
@@ -903,7 +903,7 @@ public static function selectizeHtml(array $config): string
     public static function selectizeFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'selectize' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/selectize', $config);
+        return static::fieldHtml('template:_includes/forms/selectize.twig', $config);
     }
 
     /**
@@ -915,7 +915,7 @@ public static function selectizeFieldHtml(array $config): string
      */
     public static function multiSelectHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/multiselect', $config);
+        return static::renderTemplate('_includes/forms/multiselect.twig', $config);
     }
 
     /**
@@ -929,7 +929,7 @@ public static function multiSelectHtml(array $config): string
     public static function multiSelectFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'multiselect' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/multiselect', $config);
+        return static::fieldHtml('template:_includes/forms/multiselect.twig', $config);
     }
 
     /**
@@ -942,7 +942,7 @@ public static function multiSelectFieldHtml(array $config): string
      */
     public static function textHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/text', $config);
+        return static::renderTemplate('_includes/forms/text.twig', $config);
     }
 
     /**
@@ -956,7 +956,7 @@ public static function textHtml(array $config): string
     public static function textFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'text' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/text', $config);
+        return static::fieldHtml('template:_includes/forms/text.twig', $config);
     }
 
     /**
@@ -969,7 +969,7 @@ public static function textFieldHtml(array $config): string
      */
     public static function textareaHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/textarea', $config);
+        return static::renderTemplate('_includes/forms/textarea.twig', $config);
     }
 
     /**
@@ -983,7 +983,7 @@ public static function textareaHtml(array $config): string
     public static function textareaFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'textarea' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/textarea', $config);
+        return static::fieldHtml('template:_includes/forms/textarea.twig', $config);
     }
 
     /**
@@ -996,7 +996,7 @@ public static function textareaFieldHtml(array $config): string
      */
     public static function dateHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/date', $config);
+        return static::renderTemplate('_includes/forms/date.twig', $config);
     }
 
     /**
@@ -1010,7 +1010,7 @@ public static function dateHtml(array $config): string
     public static function dateFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'date' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/date', $config);
+        return static::fieldHtml('template:_includes/forms/date.twig', $config);
     }
 
     /**
@@ -1023,7 +1023,7 @@ public static function dateFieldHtml(array $config): string
      */
     public static function timeHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/time', $config);
+        return static::renderTemplate('_includes/forms/time.twig', $config);
     }
 
     /**
@@ -1037,7 +1037,7 @@ public static function timeHtml(array $config): string
     public static function timeFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'time' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/time', $config);
+        return static::fieldHtml('template:_includes/forms/time.twig', $config);
     }
 
     /**
@@ -1051,7 +1051,7 @@ public static function timeFieldHtml(array $config): string
     public static function dateTimeFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'datetime' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/datetime', $config);
+        return static::fieldHtml('template:_includes/forms/datetime.twig', $config);
     }
 
     /**
@@ -1064,7 +1064,7 @@ public static function dateTimeFieldHtml(array $config): string
      */
     public static function elementSelectHtml(array $config): string
     {
-        return static::renderTemplate('_includes/forms/elementSelect', $config);
+        return static::renderTemplate('_includes/forms/elementSelect.twig', $config);
     }
 
     /**
@@ -1078,7 +1078,7 @@ public static function elementSelectHtml(array $config): string
     public static function elementSelectFieldHtml(array $config): string
     {
         $config['id'] = $config['id'] ?? 'elementselect' . mt_rand();
-        return static::fieldHtml('template:_includes/forms/elementSelect', $config);
+        return static::fieldHtml('template:_includes/forms/elementSelect.twig', $config);
     }
 
     /**
@@ -1115,7 +1115,7 @@ public static function autosuggestFieldHtml(array $config): string
             }
         }
 
-        return static::fieldHtml('template:_includes/forms/autosuggest', $config);
+        return static::fieldHtml('template:_includes/forms/autosuggest.twig', $config);
     }
 
     /**
diff --git a/src/mail/Mailer.php b/src/mail/Mailer.php
index 93d534647ee..d79a3d252b1 100644
--- a/src/mail/Mailer.php
+++ b/src/mail/Mailer.php
@@ -138,7 +138,7 @@ public function send($message): bool
                 $templateMode = View::TEMPLATE_MODE_SITE;
             } else {
                 // Default to the _special/email.html template
-                $template = '_special/email';
+                $template = '_special/email.twig';
                 $templateMode = View::TEMPLATE_MODE_CP;
             }
 
diff --git a/src/mail/transportadapters/Gmail.php b/src/mail/transportadapters/Gmail.php
index bd205f20c39..bf078bf4a03 100644
--- a/src/mail/transportadapters/Gmail.php
+++ b/src/mail/transportadapters/Gmail.php
@@ -88,7 +88,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Gmail/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Gmail/settings.twig', [
             'adapter' => $this,
         ]);
     }
diff --git a/src/mail/transportadapters/Sendmail.php b/src/mail/transportadapters/Sendmail.php
index 464fe65d616..2b1e465acbf 100644
--- a/src/mail/transportadapters/Sendmail.php
+++ b/src/mail/transportadapters/Sendmail.php
@@ -107,7 +107,7 @@ public function getSettingsHtml(): ?string
             ];
         }, $this->_allowedCommands());
 
-        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Sendmail/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Sendmail/settings.twig', [
             'adapter' => $this,
             'commandOptions' => $commandOptions,
         ]);
diff --git a/src/mail/transportadapters/Smtp.php b/src/mail/transportadapters/Smtp.php
index 9ce03c7326e..41e74668de9 100644
--- a/src/mail/transportadapters/Smtp.php
+++ b/src/mail/transportadapters/Smtp.php
@@ -138,7 +138,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Smtp/settings', [
+        return Craft::$app->getView()->renderTemplate('_components/mailertransportadapters/Smtp/settings.twig', [
             'adapter' => $this,
         ]);
     }
diff --git a/src/templates/_components/utilities/Upgrade.html b/src/templates/_components/utilities/Upgrade.twig
similarity index 100%
rename from src/templates/_components/utilities/Upgrade.html
rename to src/templates/_components/utilities/Upgrade.twig
diff --git a/src/utilities/AssetIndexes.php b/src/utilities/AssetIndexes.php
index 8056952dd38..097fe4c5583 100644
--- a/src/utilities/AssetIndexes.php
+++ b/src/utilities/AssetIndexes.php
@@ -61,7 +61,7 @@ public static function contentHtml(): string
         }
 
         $view = Craft::$app->getView();
-        $checkboxSelectHtml = $view->renderTemplate('_includes/forms/checkboxSelect', [
+        $checkboxSelectHtml = $view->renderTemplate('_includes/forms/checkboxSelect.twig', [
             'class' => 'first',
             'name' => 'volumes',
             'options' => $volumeOptions,
@@ -74,7 +74,7 @@ public static function contentHtml(): string
 
         $existingIndexingSessions = Craft::$app->getAssetIndexer()->getExistingIndexingSessions();
 
-        return $view->renderTemplate('_components/utilities/AssetIndexes', [
+        return $view->renderTemplate('_components/utilities/AssetIndexes.twig', [
             'existingSessions' => $existingIndexingSessions,
             'checkboxSelectHtml' => $checkboxSelectHtml,
             'dateFormat' => $dateFormat,
diff --git a/src/utilities/ClearCaches.php b/src/utilities/ClearCaches.php
index 414e76b0273..98ab494de2c 100644
--- a/src/utilities/ClearCaches.php
+++ b/src/utilities/ClearCaches.php
@@ -106,7 +106,7 @@ public static function contentHtml(): string
         $view->registerAssetBundle(ClearCachesAsset::class);
         $view->registerJs('new Craft.ClearCachesUtility(\'clear-caches\');');
 
-        return $view->renderTemplate('_components/utilities/ClearCaches', [
+        return $view->renderTemplate('_components/utilities/ClearCaches.twig', [
             'cacheOptions' => $cacheOptions,
             'tagOptions' => $tagOptions,
         ]);
diff --git a/src/utilities/DbBackup.php b/src/utilities/DbBackup.php
index 257dc20bb82..50bc5494260 100644
--- a/src/utilities/DbBackup.php
+++ b/src/utilities/DbBackup.php
@@ -53,6 +53,6 @@ public static function contentHtml(): string
         $view->registerAssetBundle(DbBackupAsset::class);
         $view->registerJs('new Craft.DbBackupUtility(\'db-backup\');');
 
-        return $view->renderTemplate('_components/utilities/DbBackup');
+        return $view->renderTemplate('_components/utilities/DbBackup.twig');
     }
 }
diff --git a/src/utilities/DeprecationErrors.php b/src/utilities/DeprecationErrors.php
index c023f528260..1456f65bbf2 100644
--- a/src/utilities/DeprecationErrors.php
+++ b/src/utilities/DeprecationErrors.php
@@ -60,7 +60,7 @@ public static function contentHtml(): string
 
         $view->registerAssetBundle(DeprecationErrorsAsset::class);
 
-        return $view->renderTemplate('_components/utilities/DeprecationErrors', [
+        return $view->renderTemplate('_components/utilities/DeprecationErrors/index.twig', [
             'logs' => Craft::$app->getDeprecator()->getLogs(),
         ]);
     }
diff --git a/src/utilities/FindAndReplace.php b/src/utilities/FindAndReplace.php
index a9348acc3c2..20083d295ab 100644
--- a/src/utilities/FindAndReplace.php
+++ b/src/utilities/FindAndReplace.php
@@ -53,6 +53,6 @@ public static function contentHtml(): string
         $view->registerAssetBundle(FindReplaceAsset::class);
         $view->registerJs('new Craft.FindAndReplaceUtility(\'find-replace\');');
 
-        return $view->renderTemplate('_components/utilities/FindAndReplace');
+        return $view->renderTemplate('_components/utilities/FindAndReplace.twig');
     }
 }
diff --git a/src/utilities/Migrations.php b/src/utilities/Migrations.php
index da16650d6e1..7b9328ee599 100644
--- a/src/utilities/Migrations.php
+++ b/src/utilities/Migrations.php
@@ -62,7 +62,7 @@ public static function contentHtml(): string
         $migrationHistory = $migrator->getMigrationHistory();
         $newMigrations = $migrator->getNewMigrations();
 
-        return $view->renderTemplate('_components/utilities/Migrations', [
+        return $view->renderTemplate('_components/utilities/Migrations.twig', [
             'migrationHistory' => $migrationHistory,
             'newMigrations' => $newMigrations,
         ]);
diff --git a/src/utilities/PhpInfo.php b/src/utilities/PhpInfo.php
index dc8a068efaa..7de1d71cf6b 100644
--- a/src/utilities/PhpInfo.php
+++ b/src/utilities/PhpInfo.php
@@ -47,7 +47,7 @@ public static function iconPath(): ?string
      */
     public static function contentHtml(): string
     {
-        return Craft::$app->getView()->renderTemplate('_components/utilities/PhpInfo', [
+        return Craft::$app->getView()->renderTemplate('_components/utilities/PhpInfo.twig', [
             'phpInfo' => self::_phpInfo(),
         ]);
     }
diff --git a/src/utilities/ProjectConfig.php b/src/utilities/ProjectConfig.php
index c31e648d794..c0f5df3e265 100644
--- a/src/utilities/ProjectConfig.php
+++ b/src/utilities/ProjectConfig.php
@@ -67,7 +67,7 @@ public static function contentHtml(): string
             $invert = false;
         }
 
-        return $view->renderTemplate('_components/utilities/ProjectConfig', [
+        return $view->renderTemplate('_components/utilities/ProjectConfig.twig', [
             'readOnly' => $projectConfig->readOnly,
             'invert' => $invert,
             'yamlExists' => $projectConfig->writeYamlAutomatically || $projectConfig->getDoesExternalConfigExist(),
diff --git a/src/utilities/QueueManager.php b/src/utilities/QueueManager.php
index 0f66d9f7020..aa56b77aa66 100644
--- a/src/utilities/QueueManager.php
+++ b/src/utilities/QueueManager.php
@@ -49,7 +49,7 @@ public static function iconPath(): ?string
      */
     public static function toolbarHtml(): string
     {
-        return Craft::$app->getView()->renderTemplate('_components/utilities/QueueManager/toolbar');
+        return Craft::$app->getView()->renderTemplate('_components/utilities/QueueManager/toolbar.twig');
     }
 
     /**
@@ -57,7 +57,7 @@ public static function toolbarHtml(): string
      */
     public static function footerHtml(): string
     {
-        return Craft::$app->getView()->renderTemplate('_components/utilities/QueueManager/footer');
+        return Craft::$app->getView()->renderTemplate('_components/utilities/QueueManager/footer.twig');
     }
 
     /**
@@ -67,6 +67,6 @@ public static function contentHtml(): string
     {
         $view = Craft::$app->getView();
         $view->registerAssetBundle(QueueManagerAsset::class);
-        return $view->renderTemplate('_components/utilities/QueueManager/content');
+        return $view->renderTemplate('_components/utilities/QueueManager/content.twig');
     }
 }
diff --git a/src/utilities/SystemMessages.php b/src/utilities/SystemMessages.php
index e200e80e157..f6929391fa7 100644
--- a/src/utilities/SystemMessages.php
+++ b/src/utilities/SystemMessages.php
@@ -55,7 +55,7 @@ public static function contentHtml(): string
 
         $messages = Craft::$app->getSystemMessages()->getAllMessages();
 
-        return $view->renderTemplate('_components/utilities/SystemMessages', [
+        return $view->renderTemplate('_components/utilities/SystemMessages/index.twig', [
             'messages' => $messages,
         ]);
     }
diff --git a/src/utilities/SystemReport.php b/src/utilities/SystemReport.php
index 7bd3cb87d21..4b386be02b9 100644
--- a/src/utilities/SystemReport.php
+++ b/src/utilities/SystemReport.php
@@ -83,7 +83,7 @@ public static function contentHtml(): string
         }
         ksort($aliases);
 
-        return Craft::$app->getView()->renderTemplate('_components/utilities/SystemReport', [
+        return Craft::$app->getView()->renderTemplate('_components/utilities/SystemReport.twig', [
             'appInfo' => self::_appInfo(),
             'plugins' => Craft::$app->getPlugins()->getAllPlugins(),
             'modules' => $modules,
diff --git a/src/utilities/Updates.php b/src/utilities/Updates.php
index 173e33fc9c8..5cb3d186293 100644
--- a/src/utilities/Updates.php
+++ b/src/utilities/Updates.php
@@ -59,6 +59,6 @@ public static function contentHtml(): string
         $view = Craft::$app->getView();
         $view->registerAssetBundle(UpdatesAsset::class);
         $view->registerJs('new Craft.UpdatesUtility();');
-        return $view->renderTemplate('_components/utilities/Updates');
+        return $view->renderTemplate('_components/utilities/Updates.twig');
     }
 }
diff --git a/src/utilities/Upgrade.php b/src/utilities/Upgrade.php
index 1709cec11df..c2a363234bb 100644
--- a/src/utilities/Upgrade.php
+++ b/src/utilities/Upgrade.php
@@ -75,6 +75,6 @@ public static function contentHtml(): string
             [$version, $allPlugins],
         ]);
 
-        return $view->renderTemplate('_components/utilities/Upgrade');
+        return $view->renderTemplate('_components/utilities/Upgrade.twig');
     }
 }
diff --git a/src/web/CpScreenResponseFormatter.php b/src/web/CpScreenResponseFormatter.php
index 08c2094ced1..16d833193ed 100644
--- a/src/web/CpScreenResponseFormatter.php
+++ b/src/web/CpScreenResponseFormatter.php
@@ -63,7 +63,7 @@ private function _formatJson(\yii\web\Request $request, YiiResponse $response, C
 
         $notice = $behavior->notice ? $view->namespaceInputs($behavior->notice, $namespace) : null;
 
-        $tabs = count($behavior->tabs) > 1 ? $view->namespaceInputs(fn() => $view->renderTemplate('_includes/tabs', [
+        $tabs = count($behavior->tabs) > 1 ? $view->namespaceInputs(fn() => $view->renderTemplate('_includes/tabs.twig', [
             'tabs' => $behavior->tabs,
         ], View::TEMPLATE_MODE_CP), $namespace) : null;
 
diff --git a/src/web/View.php b/src/web/View.php
index 82738824252..f7b02c3e378 100644
--- a/src/web/View.php
+++ b/src/web/View.php
@@ -1514,7 +1514,7 @@ public function setTemplateMode(string $templateMode): void
         // Update everything
         if ($templateMode == self::TEMPLATE_MODE_CP) {
             $this->setTemplatesPath(Craft::$app->getPath()->getCpTemplatesPath());
-            $this->_defaultTemplateExtensions = ['html', 'twig'];
+            $this->_defaultTemplateExtensions = ['twig', 'html'];
             $this->_indexTemplateFilenames = ['index'];
         } else {
             $this->setTemplatesPath(Craft::$app->getPath()->getSiteTemplatesPath());
diff --git a/src/widgets/CraftSupport.php b/src/widgets/CraftSupport.php
index 056b2436a61..3d402ab9997 100644
--- a/src/widgets/CraftSupport.php
+++ b/src/widgets/CraftSupport.php
@@ -141,7 +141,7 @@ public function getBodyHtml(): ?string
         // Only show the DB backup option if DB backups haven't been disabled
         $showBackupOption = (Craft::$app->getConfig()->getGeneral()->backupCommand !== false);
 
-        return $view->renderTemplate('_components/widgets/CraftSupport/body', [
+        return $view->renderTemplate('_components/widgets/CraftSupport/body.twig', [
             'widget' => $this,
             'buoeyIcon' => file_get_contents($iconsDir . '/buoey.svg'),
             'bullhornIcon' => file_get_contents($iconsDir . '/bullhorn.svg'),
diff --git a/src/widgets/Feed.php b/src/widgets/Feed.php
index 838f103da22..4514c061ed0 100644
--- a/src/widgets/Feed.php
+++ b/src/widgets/Feed.php
@@ -81,7 +81,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/widgets/Feed/settings',
+        return Craft::$app->getView()->renderTemplate('_components/widgets/Feed/settings.twig',
             [
                 'widget' => $this,
             ]);
@@ -125,7 +125,7 @@ public function getBodyHtml(): ?string
             );
         }
 
-        return Craft::$app->getView()->renderTemplate('_components/widgets/Feed/body', [
+        return Craft::$app->getView()->renderTemplate('_components/widgets/Feed/body.twig', [
             'feed' => $data,
         ]);
     }
diff --git a/src/widgets/NewUsers.php b/src/widgets/NewUsers.php
index 9f9a19308f9..ed9b639e0a6 100644
--- a/src/widgets/NewUsers.php
+++ b/src/widgets/NewUsers.php
@@ -95,7 +95,7 @@ public function getBodyHtml(): ?string
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/widgets/NewUsers/settings',
+        return Craft::$app->getView()->renderTemplate('_components/widgets/NewUsers/settings.twig',
             [
                 'widget' => $this,
             ]);
diff --git a/src/widgets/QuickPost.php b/src/widgets/QuickPost.php
index 44ed47fa721..db30458e3c9 100644
--- a/src/widgets/QuickPost.php
+++ b/src/widgets/QuickPost.php
@@ -117,7 +117,7 @@ public function getSettingsHtml(): ?string
             }
         }
 
-        return Craft::$app->getView()->renderTemplate('_components/widgets/QuickPost/settings',
+        return Craft::$app->getView()->renderTemplate('_components/widgets/QuickPost/settings.twig',
             [
                 'sections' => $sections,
                 'fieldsByEntryTypeId' => $fieldsByEntryTypeId,
@@ -175,7 +175,7 @@ public function getBodyHtml(): ?string
 
         $view->startJsBuffer();
 
-        $html = $view->renderTemplate('_components/widgets/QuickPost/body',
+        $html = $view->renderTemplate('_components/widgets/QuickPost/body.twig',
             [
                 'section' => $section,
                 'entryType' => $entryType,
diff --git a/src/widgets/RecentEntries.php b/src/widgets/RecentEntries.php
index b1524f2b177..95a0c4587d5 100644
--- a/src/widgets/RecentEntries.php
+++ b/src/widgets/RecentEntries.php
@@ -81,7 +81,7 @@ protected function defineRules(): array
      */
     public function getSettingsHtml(): ?string
     {
-        return Craft::$app->getView()->renderTemplate('_components/widgets/RecentEntries/settings',
+        return Craft::$app->getView()->renderTemplate('_components/widgets/RecentEntries/settings.twig',
             [
                 'widget' => $this,
             ]);
@@ -143,7 +143,7 @@ public function getBodyHtml(): ?string
 
         $entries = $this->_getEntries();
 
-        return $view->renderTemplate('_components/widgets/RecentEntries/body',
+        return $view->renderTemplate('_components/widgets/RecentEntries/body.twig',
             [
                 'entries' => $entries,
             ]);
diff --git a/src/widgets/Updates.php b/src/widgets/Updates.php
index 7435f545ad0..7acc2a478cb 100644
--- a/src/widgets/Updates.php
+++ b/src/widgets/Updates.php
@@ -71,7 +71,7 @@ public function getBodyHtml(): ?string
         }
 
         if ($cached) {
-            return $view->renderTemplate('_components/widgets/Updates/body',
+            return $view->renderTemplate('_components/widgets/Updates/body.twig',
                 [
                     'total' => Craft::$app->getUpdates()->getTotalAvailableUpdates(),
                 ]);
diff --git a/tests/unit/web/ControllerTest.php b/tests/unit/web/ControllerTest.php
index 2bc43e1eb62..424f29a7235 100644
--- a/tests/unit/web/ControllerTest.php
+++ b/tests/unit/web/ControllerTest.php
@@ -64,7 +64,7 @@ public function testTemplateRendering(): void
         // We need to render a template from the site dir.
         Craft::$app->getView()->setTemplateMode(View::TEMPLATE_MODE_SITE);
 
-        $response = $this->controller->renderTemplate('template');
+        $response = $this->controller->renderTemplate('template.twig');
         (new TemplateResponseFormatter())->format($response);
 
         // Again. If this is all good. We can expect Yii to do its thing.
@@ -84,7 +84,7 @@ public function testTemplateRenderingIfHeadersAlreadySet(): void
         Craft::$app->getView()->setTemplateMode(View::TEMPLATE_MODE_SITE);
         Craft::$app->getResponse()->getHeaders()->set('content-type', 'HEADERS');
 
-        $response = $this->controller->renderTemplate('template');
+        $response = $this->controller->renderTemplate('template.twig');
         (new TemplateResponseFormatter())->format($response);
 
         // Again. If this is all good. We can expect Yii to do its thing.
diff --git a/tests/unit/web/ViewTest.php b/tests/unit/web/ViewTest.php
index 60f17be9fef..a07c9d29e68 100644
--- a/tests/unit/web/ViewTest.php
+++ b/tests/unit/web/ViewTest.php
@@ -149,13 +149,13 @@ public function testRenderTemplate(): void
         // Assert that the _renderingTemplate prop goes in and comes out as null.
         self::assertNull($this->getInaccessibleProperty($this->view, '_renderingTemplate'));
 
-        $result = $this->view->renderTemplate('withvar', ['name' => 'Giel Tettelaar']);
+        $result = $this->view->renderTemplate('withvar.twig', ['name' => 'Giel Tettelaar']);
 
         self::assertSame($result, 'Hello iam Giel Tettelaar');
         self::assertNull($this->getInaccessibleProperty($this->view, '_renderingTemplate'));
 
         // Test that templates can work without variables.
-        $result = $this->view->renderTemplate('novar');
+        $result = $this->view->renderTemplate('novar.twig');
 
         self::assertSame($result, 'I have no vars');
     }
@@ -219,7 +219,7 @@ public function testSetCpTemplateMode(): void
         );
 
         self::assertSame(
-            ['html', 'twig'],
+            ['twig', 'html'],
             $this->getInaccessibleProperty($this->view, '_defaultTemplateExtensions')
         );