InvalidBasesError: Cannot resolve bases for [<ModelState: 'users.GroupProxy'>]
After a lot of digging on this the only thing that worked for me was
comment out the offending apps, run migrations, then add them in again.
Just a workaround but hopefully it helps somebody.
Simply creating a migrations directory at the root of your app (so users/migrations/ in your case) and adding an empty __init__.py file might resolve your issue. At least it did for me when I was getting the same error.
But you're better off running makemigrations for your app, as suggested by @zenofewords above. That will create the directory for you AND generate migrations for your proxy models.
Why does Django create migration files for proxy models?
Your tests are looking for those migrations and aren't finding them.
I've come across this issue, and as commenting out the model isn't really a solution, I've found that setting the undocumented auto_created = True to the Meta class will make Django ignore it.
class GroupProxy(Group): class Meta: proxy = True auto_created = True