          migrations.CreateModel(
              name='B2',
              fields=[
                  ('id', models.AutoField(primary_key=True, verbose_name='ID', auto_created=True, serialize=False)),
                  ('a1', models.ForeignKey(to='lookuperror_a.A1')),
              ],
          ),
      ]
 
</s> remove                 ('a1', models.ForeignKey(to='lookuperror_a.A1')),
 </s> add                 ('a1', models.ForeignKey('lookuperror_a.A1', models.CASCADE)), </s> remove                 ('b2', models.ForeignKey(to='lookuperror_b.B2')),
                ('c2', models.ForeignKey(to='lookuperror_c.C2')),
 </s> add                 ('b2', models.ForeignKey('lookuperror_b.B2', models.CASCADE)),
                ('c2', models.ForeignKey('lookuperror_c.C2', models.CASCADE)), </s> remove                 ('author', models.ForeignKey('author_app.Author')),
 </s> add                 ('author', models.ForeignKey('author_app.Author', models.CASCADE)), </s> remove             ('neighborhood', models.ForeignKey(to='gis_migrations.Neighborhood', to_field='id', null=True)),
 </s> add             ('neighborhood', models.ForeignKey(
                'gis_migrations.Neighborhood',
                models.SET_NULL,
                to_field='id',
                null=True,
            )), </s> remove                 ('content_type', models.ForeignKey(to='contenttypes.ContentType', to_field='id', verbose_name='content type')),
 </s> add                 ('content_type', models.ForeignKey(
                    to='contenttypes.ContentType',
                    on_delete=models.CASCADE,
                    to_field='id',
                    verbose_name='content type',
                )),
                ('a1', models.ForeignKey('lookuperror_a.A1', models.CASCADE)),
          migrations.CreateModel(
              name='B2',
              fields=[
                  ('id', models.AutoField(primary_key=True, verbose_name='ID', auto_created=True, serialize=False)),
                ('a1', models.ForeignKey('lookuperror_a.A1', models.CASCADE)),
              ],
          ),
      ]
keep keep keep keep replace keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/migrations/migrations_test_apps/lookuperror_b/migrations/0002_b2.py