Django 1.7 throws django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet

Running these commands solved my problem (credit to this answer):

import django
django.setup()

However I'm not sure why I need this. Comments would be appreciated.

This is what solved it for us and these folks:

Our project started with Django 1.4, we went to 1.5 and then to 1.7. Our wsgi.py looked like this:

import os

from django.core.handlers.wsgi import WSGIHandler

os.environ['DJANGO_SETTINGS_MODULE'] = 'myapp.settings'
application = WSGIHandler()

When I updated to the 1.7 style WSGI handler:

import os

from django.core.wsgi import get_wsgi_application

os.environ['DJANGO_SETTINGS_MODULE'] = 'myapp.settings'
application = get_wsgi_application()

Everything works now.

The issue is in your registration app. It seems django-registration calls get_user_module() in models.py at a module level (when models are still being loaded by the application registration process). This will no longer work:

try:
    from django.contrib.auth import get_user_model
    User = get_user_model()
except ImportError:
    from django.contrib.auth.models import User    

I'd change this models file to only call get_user_model() inside methods (and not at module level) and in FKs use something like:

user = ForeignKey(settings.AUTH_USER_MODEL)

BTW, the call to django.setup() shouldn't be required in your manage.py file, it's called for you in execute_from_command_line. (source)