In Django < 1.7, if settings.AUTH_USER_MODEL is defined, the sender is expected to be the actual instance, not a string. This Closes rossp/django-helpdesk#295 by checking for django version < 1.7.

helpdesk/models.py

@@ -1041,6 +1041,10 @@ def create_usersettings(sender, instance, created, **kwargs):
         UserSettings.objects.create(user=instance, settings=DEFAULT_USER_SETTINGS)
 
 try:
+    # Connecting via settings.AUTH_USER_MODEL (string) fails in Django < 1.7. We need the actual model there.
+    # https://docs.djangoproject.com/en/1.7/topics/auth/customizing/#referencing-the-user-model
+    if django.VERSION < (1, 7):
+        raise ValueError
     models.signals.post_save.connect(create_usersettings, sender=settings.AUTH_USER_MODEL)
 except:
     signal_user = get_user_model()