      pass
  
  
  class A3(models.Model):
      b2 = models.ForeignKey('lookuperror_b.B2')
      c2 = models.ForeignKey('lookuperror_c.C2')
  
  
  class A4(models.Model):
      pass
 
</s> remove     a1 = models.ForeignKey('lookuperror_a.A1')
 </s> add     a1 = models.ForeignKey('lookuperror_a.A1', models.CASCADE) </s> remove     a1 = models.ForeignKey('lookuperror_a.A1')
 </s> add     a1 = models.ForeignKey('lookuperror_a.A1', models.CASCADE) </s> remove     title = models.ForeignKey(Title)
 </s> add     title = models.ForeignKey(Title, models.CASCADE) </s> remove     recommender = models.ForeignKey(Recommender)
 </s> add     recommender = models.ForeignKey(Recommender, models.CASCADE) </s> remove             parent = models.ForeignKey(Parent)
 </s> add             parent = models.ForeignKey(Parent, models.CASCADE)
    b2 = models.ForeignKey('lookuperror_b.B2', models.CASCADE)
    c2 = models.ForeignKey('lookuperror_c.C2', models.CASCADE)
      pass
  
  
  class A3(models.Model):
    b2 = models.ForeignKey('lookuperror_b.B2', models.CASCADE)
    c2 = models.ForeignKey('lookuperror_c.C2', models.CASCADE)
    b2 = models.ForeignKey('lookuperror_b.B2', models.CASCADE)
    c2 = models.ForeignKey('lookuperror_c.C2', models.CASCADE)
  
  
  class A4(models.Model):
      pass
keep keep keep keep replace replace keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/migrations/migrations_test_apps/lookuperror_a/models.py