python - Django 1.8 Migrations - "NoneType" object has no attribute "_meta" -

attempting migrate project django 1.7 1.8. after wrestling code errors, i'm able migrations run. however, when try migrate, i'm given error "'nonetype' object has no attribute '_meta'"

there's no reference in traceback of apps, i'm unsure of go looking bug (as code include here can more helpful trying me)

here's full text of traceback

(venv)rtownley@ubuntu:~/projects/sparrow1/nj$ ./manage.py makemigrations no changes detected (venv)rtownley@ubuntu:~/projects/sparrow1/nj$ ./manage.py migrate operations perform:   synchronize unmigrated apps: staticfiles, editor, djcelery, messages, getty, kombu_transport_django, debug_toolbar, utils, locking, petro, tokenapi, grappelli, django_extensions, selectable   apply migrations: adops, taxonomy, issues, editorial, contenttypes, authors, auth, comms, membership, sessions, bento, urlalias, accounts, breaking_news, easy_thumbnails, images, admin, pages, documents, events synchronizing apps without migrations:   creating tables...     running deferred sql...   installing custom sql... running migrations:   rendering model states...traceback (most recent call last):   file "./manage.py", line 10, in <module>     execute_from_command_line(sys.argv)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line     utility.execute()   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/__init__.py", line 330, in execute     self.fetch_command(subcommand).run_from_argv(self.argv)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/base.py", line 390, in run_from_argv     self.execute(*args, **cmd_options)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/base.py", line 441, in execute     output = self.handle(*args, **options)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/core/management/commands/migrate.py", line 221, in handle     executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/executor.py", line 104, in migrate     state = migration.mutate_state(state, preserve=do_run)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/migration.py", line 83, in mutate_state     operation.state_forwards(self.app_label, new_state)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/operations/fields.py", line 51, in state_forwards     state.reload_model(app_label, self.model_name_lower)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/state.py", line 97, in reload_model     related_models = get_related_models_recursive(old_model)   file "/home/rtownley/projects/sparrow1/venv/lib/python3.4/site-packages/django/db/migrations/state.py", line 57, in get_related_models_recursive     rel_app_label, rel_model_name = rel_mod._meta.app_label, rel_mod._meta.model_name attributeerror: 'nonetype' object has no attribute '_meta' 

other pieces potentially @ play: -i have custom handler listens save event, serializes data, , creates identical object in mongo -operating out of virtual environment running python3.4

any thoughts on go hunting error? thanks, , sorry can't provide more code yet!

thanks meiamsome, figured out: 1 of models had foreignkey relationship model no longer existed (i had removed it, , git merge had added back). all!