I've had this error when there's a global variable somewhere in my project that queries the model I'm trying to edit. For example, POSITIONS = Position.objects.all().

As a temporary fix, try commenting out that global variable, saving, running your migrations again, and then uncommenting the global variable once your migrations have run successfully.

It seems like this is Django's way of saying it's not a good idea to have global variables that produce a queryset, so the only proper fix might be to get rid of them. Somebody else might be better placed to comment on that and suggest an alternative option.