django.db.utils.IntegrityError: The row in table ‘%’ with primary key '1' has an invalid foreign key: %.user_id contains a value '1' that does not have a corresponding value in auth_user.id.

This is on a Django / Wagtail project.  Although I think the issue is relevant only to the Django side of it here. 

I was getting this error when running some tests on my APP .

python3 manage.py test tasks

The error :
django.db.utils.IntegrityError: The row in table ‘%’ with primary key '1' has an invalid foreign key: %.user_id contains a value '1' that does not have a corresponding value in auth_user.id.

The offending code :

django models.ForeignKey(User, on_delete=models.CASCADE, default=1)

Here's what I searched when looking for an answer:

Django how to add a default user id to model

Django model foreignKey user pass in default user

Django does not have a corresponding value in auth_user.id


I tried a few different methods to resolve including removing all my migration file and running the migrate commands again .

python3 manage.py makemigrations

Python3 manage.py migrate

What I found worked though was to change my code to the following line ( and then run the above migration commands again )

user = models.ForeignKey(User, on_delete=models.CASCADE, blank=True, null=True)