`RecursionError` when deleting a model instance in Admin

Using Django Using the ORM
12

I’m still not able to recreate the problem you’re describing. Here are the classes I’m using:

class PStatus(models.Model):
    statustext = models.CharField(max_length=20, blank=True)

class Department(models.Model):
    name = models.CharField(max_length=50)

class Erfasst(models.Model):
    status      = models.ForeignKey(PStatus, models.PROTECT)
    approved_at = models.DateTimeField(null=True, blank=True)
    dept = models.ForeignKey(Department, models.SET_NULL, null=True, blank=True)

    @classmethod
    def from_db(cls, db, field_names, values):
        instance = super().from_db(db, field_names, values)
        instance._old_status_id = instance.status_id
        instance._old_approved_at = instance.approved_at
        return instance

Deleting an entry from Department that is being referenced by Erfasst causes the dept field to be set to null as expected.