diff --git a/docs/qppe-server.yaml b/docs/qppe-server.yaml
index d4bebfa..894a59b 100644
--- a/docs/qppe-server.yaml
+++ b/docs/qppe-server.yaml
@@ -106,7 +106,9 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/QuestionCreated"
-        400:
+        404:
+          description: Package not found.
+        422:
           description: Validation error
           headers:
             Content-Language:
@@ -114,9 +116,7 @@ paths:
           content:
             application/json:
               schema:
-                type: object
-        404:
-          description: Package not found.
+                $ref: "#/components/schemas/OptionsFormValidationError"
         500:
           description: Error occurred.
           content:
@@ -1067,6 +1067,14 @@ components:
           description: Optional human-readable reason for the error.
       required: [ error_code, temporary ]
 
+    OptionsFormValidationError:
+      allOf:
+        - $ref: "#/components/schemas/RequestError"
+        - type: object
+          properties:
+            errors:
+              type: object
+
     QuestionStateMigrationError:
       type: object
       properties:
diff --git a/questionpy_server/models.py b/questionpy_server/models.py
index f594833..58f8b7f 100644
--- a/questionpy_server/models.py
+++ b/questionpy_server/models.py
@@ -99,6 +99,7 @@ class RequestErrorCode(Enum):
     INVALID_QUESTION_STATE = "INVALID_QUESTION_STATE"
     INVALID_PACKAGE = "INVALID_PACKAGE"
     INVALID_REQUEST = "INVALID_REQUEST"
+    INVALID_OPTIONS_FORM = "INVALID_OPTIONS_FORM"
     PACKAGE_ERROR = "PACKAGE_ERROR"
     PACKAGE_NOT_FOUND = "PACKAGE_NOT_FOUND"
     CALLBACK_API_ERROR = "CALLBACK_API_ERROR"
@@ -113,6 +114,10 @@ class RequestError(BaseModel):
     reason: str | None = None
 
 
+class OptionsFormValidationError(RequestError):
+    errors: dict[str, str]
+
+
 class QuestionStateMigrationErrorCode(Enum):
     NOT_IMPLEMENTED = "NOT_IMPLEMENTED"
     DOWNGRADE_NOT_POSSIBLE = "DOWNGRADE_NOT_POSSIBLE"
diff --git a/questionpy_server/web/_middlewares.py b/questionpy_server/web/_middlewares.py
index 155fce0..610259c 100644
--- a/questionpy_server/web/_middlewares.py
+++ b/questionpy_server/web/_middlewares.py
@@ -10,7 +10,7 @@
 from aiohttp.web_response import StreamResponse
 
 import questionpy_server.web.errors as web_error
-from questionpy_common.api.qtype import InvalidAttemptStateError, InvalidQuestionStateError
+from questionpy_common.api.qtype import InvalidAttemptStateError, InvalidQuestionStateError, OptionsFormValidationError
 from questionpy_common.error import QPyBaseError
 from questionpy_server.worker.exception import (
     StaticFileSizeMismatchError,
@@ -50,6 +50,8 @@ async def error_middleware(request: Request, handler: Handler) -> StreamResponse
     except tuple(exception_map.keys()) as e:
         exception = exception_map[type(e)]
         return exception(reason=e.reason, temporary=e.temporary)
+    except OptionsFormValidationError as e:
+        return web_error.InvalidOptionsFormError(reason=e.reason, errors=e.errors)
     except Exception:  # noqa: BLE001
         web_logger.exception("There was an unexpected error while processing the request.")
         return web_error.ServerError(reason="unknown", temporary=True)
diff --git a/questionpy_server/web/errors.py b/questionpy_server/web/errors.py
index d9a2d82..484c9b6 100644
--- a/questionpy_server/web/errors.py
+++ b/questionpy_server/web/errors.py
@@ -6,7 +6,7 @@
 from aiohttp import web
 from aiohttp.log import web_logger
 
-from questionpy_server.models import RequestError, RequestErrorCode
+from questionpy_server.models import OptionsFormValidationError, RequestError, RequestErrorCode
 
 
 class _ExceptionMixin(web.HTTPException):
@@ -95,6 +95,19 @@ def __init__(self, *, reason: str | None, **_: Any) -> None:
         )
 
 
+class InvalidOptionsFormError(web.HTTPUnprocessableEntity, _ExceptionMixin):
+    def __init__(self, *, reason: str | None, errors: dict[str, str], **_: Any) -> None:
+        super().__init__(
+            "Invalid form data was provided",
+            OptionsFormValidationError(
+                error_code=RequestErrorCode.INVALID_OPTIONS_FORM,
+                reason=reason,
+                temporary=False,
+                errors=errors,
+            ),
+        )
+
+
 class PackageError(web.HTTPInternalServerError, _ExceptionMixin):
     def __init__(self, *, reason: str | None, temporary: bool) -> None:
         super().__init__(
diff --git a/tests/questionpy_server/web/test_error_middleware.py b/tests/questionpy_server/web/test_error_middleware.py
index 2290714..342eeb6 100644
--- a/tests/questionpy_server/web/test_error_middleware.py
+++ b/tests/questionpy_server/web/test_error_middleware.py
@@ -5,8 +5,9 @@
 from typing import Any, NoReturn
 
 import pytest
-from aiohttp import web
+from aiohttp import MultipartWriter, web
 from aiohttp.pytest_plugin import AiohttpClient
+from aiohttp.test_utils import TestClient
 from aiohttp.web_exceptions import HTTPBadRequest, HTTPException, HTTPMethodNotAllowed, HTTPNotFound
 
 from questionpy_common.api.qtype import InvalidQuestionStateError
@@ -30,6 +31,7 @@
     WorkerStartError,
 )
 from questionpy_server.worker.runtime.messages import WorkerMemoryLimitExceededError, WorkerUnknownError
+from tests.conftest import PACKAGE
 
 
 def error_server(error: Exception) -> web.Application:
@@ -156,3 +158,30 @@ async def test_unexpected_exception_should_return_server_error(
     assert logger_name == "aiohttp.web"
     assert "unexpected error" in message
     assert log_level == logging.ERROR
+
+
+async def test_invalid_options_form_data_error(client: TestClient) -> None:
+    with PACKAGE.path.open("rb") as package_fd, MultipartWriter("form-data") as writer:
+        part = writer.append(package_fd)
+        part.set_content_disposition("form-data", name="package")
+
+        part = writer.append_json({"form_data": {}})
+        part.set_content_disposition("form-data", name="main")
+
+        res = await client.post(
+            f"/packages/{PACKAGE.hash}/question",
+            data=writer,
+        )
+
+    assert res.status == 422
+    data = await res.json()
+    assert (
+        data.items()
+        >= {
+            "error_code": RequestErrorCode.INVALID_OPTIONS_FORM.value,
+            "temporary": False,
+            "reason": None,
+        }.items()
+    )
+
+    assert data["errors"].items() == {"my_hidden": "Field required", "my_repetition": "Field required"}.items()