diff --git a/src/server/BreCal/validators/validation_error.py b/src/server/BreCal/validators/validation_error.py
index cdac103..65ee985 100644
--- a/src/server/BreCal/validators/validation_error.py
+++ b/src/server/BreCal/validators/validation_error.py
@@ -27,8 +27,15 @@ def create_validation_error_response(ex:ValidationError, status_code:int=400)->t
         "errors":errors,
         "valid_data":valid_data
     }
-    return (json.dumps(json_response), status_code)
+
+    # json.dumps with default=str automatically converts non-serializable values to strings. Hence, datetime objects (which are not)
+    # natively serializable are properly serialized.
+    serialized_response = json.dumps(json_response, default=str)
+    return (serialized_response, status_code)
 
 def create_werkzeug_error_response(ex:Forbidden, status_code:int=403)->typing.Tuple[str,int]:
-    return json.dumps({"message":ex.description}), status_code
+    # json.dumps with default=str automatically converts non-serializable values to strings. Hence, datetime objects (which are not)
+    # natively serializable are properly serialized.
+    serialized_response = json.dumps({"message":ex.description}, default=str)
+    return serialized_response, status_code
 
diff --git a/src/server/tests/validators/test_validation_error.py b/src/server/tests/validators/test_validation_error.py
new file mode 100644
index 0000000..a103919
--- /dev/null
+++ b/src/server/tests/validators/test_validation_error.py
@@ -0,0 +1,19 @@
+import pytest
+
+def test_create_validation_error_response_is_serializable():
+    from BreCal.stubs.times_full import get_valid_stub_times
+    from BreCal.schemas import model
+    from BreCal.validators.validation_error import create_validation_error_response
+
+    content = get_valid_stub_times()
+
+    import datetime
+    content["operations_end"] = (datetime.datetime.now()-datetime.timedelta(minutes=14)).isoformat()
+
+    content["id"] = 3
+    try:
+        loadedModel = model.TimesSchema().load(data=content, many=False, partial=True)
+    except Exception as ex:
+        my_var = ex
+        create_validation_error_response(ex=ex, status_code=400) # this function initially created errors, as datetime objects were not serializable. Corrected now.
+    return