I really think the Django documentation should warn against using classes directly as string representation, especially when linking to the user model.
There's always room for improvement though so if you have ideas on how to make these particular error messages more helpful, please share. Please reopen it if you have a concrete proposal or if you want to point out what you think is not clear in the error messages. This exact error occurred to me before, just because of an import error in a file in another app (which is something completely unrelated).
If you're still stuck, you can reach out to our support channels  for help. Everything worked yesterday but some edit somewhere broke everything, I cannot find where, the compiler in Eclipse shows no import error in any file.
I am absolutely positive that the error message provided by Django is totally useless here : The validation only reports errors in models fields and so on.
In our situation, target, instead of using a label.
I was stuck on an issue with Serializers in Django Rest Framework for almost 7 hours yesterday. Char Field(max_length=1024) def validate_subject(self, attrs, source): return .get(attrs.get(source)) or attrs.get(source) def transform_subject(self, obj, value): return .get(obj.subject) or obj.subject class Meta: model = Book fields = ('id', 'title', 'subject', ) class Book Serializer(serializers. Char Field() def validate_subject(self, attrs, source): return .get(attrs.get(source)) or attrs.get(source) def transform_subject(self, obj, value): return .get(obj.subject) or obj.subject def restore_object(self, attrs, instance=None): if instance is None: return Book(**attrs) return instance We will run into an error with this implementation: "Attribute Error: 'dict' object has no attribute ‘save’".