Fixed #23039: Don't try to serialize unmanaged models in tests

django/db/backends/creation.py

@@ -424,7 +424,7 @@ class BaseDatabaseCreation(object):
         # Make a function to iteratively return every object
         def get_objects():
             for model in sort_dependencies(app_list):
-                if not model._meta.proxy and router.allow_migrate(self.connection.alias, model):
+                if not model._meta.proxy and model._meta.managed and router.allow_migrate(self.connection.alias, model):
                     queryset = model._default_manager.using(self.connection.alias).order_by(model._meta.pk.name)
                     for obj in queryset.iterator():
                         yield obj

tests/migration_test_data_persistence/models.py

@@ -3,3 +3,10 @@ from django.db import models
 
 class Book(models.Model):
     title = models.CharField(max_length=100)
+
+
+class Unmanaged(models.Model):
+    title = models.CharField(max_length=100)
+
+    class Meta:
+        managed = False