      def __init__(self, model):
          self.model = model
  
      def __get__(self, instance, type=None):
          raise AttributeError("Manager isn't available; %s has been swapped for '%s'" % (
              self.model._meta.object_name, self.model._meta.swapped
          ))
  
  
  class EmptyManager(Manager):
      def __init__(self, model):
          super(EmptyManager, self).__init__()
 
</s> remove                 self.fail('Should raise an AttributeError')
            except AttributeError as e:
                self.assertEqual(str(e), "Manager isn't available; SwappableModel has been swapped for 'managers_regress.Parent'")

 </s> add  </s> remove                 self.fail('Should raise an AttributeError')
            except AttributeError as e:
                self.assertEqual(str(e), "Manager isn't available; SwappableModel has been swapped for 'managers_regress.Parent'")

 </s> add  </s> remove                 self.fail('Should raise an AttributeError')
            except AttributeError as e:
                self.assertEqual(str(e), "Manager isn't available; SwappableModel has been swapped for 'managers_regress.Parent'")

 </s> add  </s> remove             try:
 </s> add             msg = (
                "Manager isn't available; 'managers_regress.SwappableModel' "
                "has been swapped for 'managers_regress.Parent'"
            )
            with self.assertRaisesMessage(AttributeError, msg): </s> remove             try:
 </s> add             msg = (
                "Manager isn't available; 'managers_regress.SwappableModel' "
                "has been swapped for 'managers_regress.Parent'"
            )
            with self.assertRaisesMessage(AttributeError, msg):
        raise AttributeError(
            "Manager isn't available; '%s.%s' has been swapped for '%s'" % (
                self.model._meta.app_label,
                self.model._meta.object_name,
                self.model._meta.swapped,
            )
        )
      def __init__(self, model):
          self.model = model
  
      def __get__(self, instance, type=None):
        raise AttributeError(
            "Manager isn't available; '%s.%s' has been swapped for '%s'" % (
                self.model._meta.app_label,
                self.model._meta.object_name,
                self.model._meta.swapped,
            )
        )
        raise AttributeError(
            "Manager isn't available; '%s.%s' has been swapped for '%s'" % (
                self.model._meta.app_label,
                self.model._meta.object_name,
                self.model._meta.swapped,
            )
        )
        raise AttributeError(
            "Manager isn't available; '%s.%s' has been swapped for '%s'" % (
                self.model._meta.app_label,
                self.model._meta.object_name,
                self.model._meta.swapped,
            )
        )
  
  
  class EmptyManager(Manager):
      def __init__(self, model):
          super(EmptyManager, self).__init__()
keep keep keep keep replace replace replace keep keep keep keep keep
 Fixed #25054 -- Added app_label to swapped model AttributeError 
django/db/models/manager.py