diff --git a/netbox/users/forms/model_forms.py b/netbox/users/forms/model_forms.py
index 6a2921b60..fef10cfe2 100644
--- a/netbox/users/forms/model_forms.py
+++ b/netbox/users/forms/model_forms.py
@@ -201,6 +201,11 @@ class UserForm(BootstrapMixin, forms.ModelForm):
             del self.fields['date_joined']
             del self.fields['last_login']
 
+    # def is_valid(self):
+    #     ret = super().is_valid()
+    #     breakpoint()
+    #     return ret
+
     def save(self, *args, **kwargs):
         instance = super().save(*args, **kwargs)
         instance.object_permissions.set(self.cleaned_data['object_permissions'])
@@ -215,9 +220,27 @@ class UserForm(BootstrapMixin, forms.ModelForm):
 
             if password != confirm_password:
                 raise forms.ValidationError(
-                    "password and confirm_password does not match"
+                    _("password and confirm_password does not match")
                 )
 
+    def clean_username(self):
+        """Reject usernames that differ only in case."""
+        instance = getattr(self, 'instance', None)
+        if instance:
+            qs = self._meta.model.objects.exclude(pk=instance.pk)
+        else:
+            qs = self._meta.model.objects.all()
+
+        username = self.cleaned_data.get("username")
+        if (
+            username and qs.filter(username__iexact=username).exists()
+        ):
+            raise forms.ValidationError(
+                _("user with this username already exists")
+            )
+
+        return username
+
 
 class GroupForm(BootstrapMixin, forms.ModelForm):
     users = DynamicModelMultipleChoiceField(
diff --git a/netbox/utilities/testing/views.py b/netbox/utilities/testing/views.py
index dc17548a2..d073b8db6 100644
--- a/netbox/utilities/testing/views.py
+++ b/netbox/utilities/testing/views.py
@@ -170,13 +170,14 @@ class ViewTestCases:
             instance = self._get_queryset().order_by('pk').last()
             self.assertInstanceEqual(instance, self.form_data)
 
-            # Verify ObjectChange creation
-            objectchanges = ObjectChange.objects.filter(
-                changed_object_type=ContentType.objects.get_for_model(instance),
-                changed_object_id=instance.pk
-            )
-            self.assertEqual(len(objectchanges), 1)
-            self.assertEqual(objectchanges[0].action, ObjectChangeActionChoices.ACTION_CREATE)
+            if hasattr(self.model, "to_objectchange"):
+                # Verify ObjectChange creation
+                objectchanges = ObjectChange.objects.filter(
+                    changed_object_type=ContentType.objects.get_for_model(instance),
+                    changed_object_id=instance.pk
+                )
+                self.assertEqual(len(objectchanges), 1)
+                self.assertEqual(objectchanges[0].action, ObjectChangeActionChoices.ACTION_CREATE)
 
         @override_settings(EXEMPT_VIEW_PERMISSIONS=['*'])
         def test_create_object_with_constrained_permission(self):
@@ -263,13 +264,14 @@ class ViewTestCases:
             self.assertHttpStatus(self.client.post(**request), 302)
             self.assertInstanceEqual(self._get_queryset().get(pk=instance.pk), self.form_data)
 
-            # Verify ObjectChange creation
-            objectchanges = ObjectChange.objects.filter(
-                changed_object_type=ContentType.objects.get_for_model(instance),
-                changed_object_id=instance.pk
-            )
-            self.assertEqual(len(objectchanges), 1)
-            self.assertEqual(objectchanges[0].action, ObjectChangeActionChoices.ACTION_UPDATE)
+            if hasattr(self.model, "to_objectchange"):
+                # Verify ObjectChange creation
+                objectchanges = ObjectChange.objects.filter(
+                    changed_object_type=ContentType.objects.get_for_model(instance),
+                    changed_object_id=instance.pk
+                )
+                self.assertEqual(len(objectchanges), 1)
+                self.assertEqual(objectchanges[0].action, ObjectChangeActionChoices.ACTION_UPDATE)
 
         @override_settings(EXEMPT_VIEW_PERMISSIONS=['*'])
         def test_edit_object_with_constrained_permission(self):