InvalidBasesError: Cannot resolve bases for []

Question

When I run tests I get this error during database initialization:

django.db.migrations.state.InvalidBasesError: Cannot resolve bases for [

        

Answer 1

I also faced this issue (after doing some complex model inheritance). One of my migrations contained

migrations.CreateModel(
    name='Offer',
    fields=[
        # ...
    ],
    options={
        # ...
    },
    bases=('shop.entity',),
),

I deleted shop.Entity model entirely, but the migration was referencing it in bases attribute. So I just deleted bases=('shop.entity',) and it works. It will probably break an opportunity to migrate from the beginning, but at least allows to migrate further on.

Another advice would be: go directly to django code and inspect what's causing "bases" trouble. Go to django/db/migrations/state.py and add a breakpoint:

try:
    bases = tuple(
        (apps.get_model(base) if isinstance(base, six.string_types) else base)
        for base in self.bases
    )
except LookupError:
    print(self.bases)  # <-- print the bases
    import ipdb; ipdb.set_trace()  # <-- debug here
    raise InvalidBasesError("Cannot resolve one or more bases from %r" % (self.bases,))