Django 1.7.3 - Lookup failed for model referenced by field

Question

I am trying create a new model with Django, but I keep running into the error Lookup failed for model referenced by field help.HelpDefinition.org: account.Organization. Organization has been imported. You can see the model below.

models.py

org = models.ForeignKey(Organization, unique=True)
help_type = models.CharField(max_length=255, choices=HELP_CHOICES)
help_content = models.TextField(blank=True)

This model has been successfully migrated previously. I dropped the table via psql in Postgres so that it could be recreated.

Answer 1

It happens when you change the target objects in relationship. Even if they have the same name and fields they are not the same objects. I had the same issue and deleting all previous migrations from migrations folder solved it.

Answer 2

You can also add as a dependency to the migration the last migration from the object's app. That did the trick for me.

class Migration(migrations.Migration):

dependencies = [
    (<app>, <last_migration_filename>),
...

Answer 3

My case was: moving away from South I deleted almost all migration files from several apps and applied makemigrations and migrate and later on I found out some forgotten migrations in one app and I tried to do the process (delete/makemigrations) only for this one app. But going back one step and recreating the migrations for ALL the apps fixed the issue for me.