Ticket #8245: Misleading-AlreadyRegistered-00.diff

django/contrib/admin/__init__.py

@@ -16 +16 @@
         except ImportError:
             # there is no app admin.py, skip it
             continue
-        __import__("%s.admin" % app)
+        try:
+            models_registered_before_import = site._registry.keys()
+            __import__("%s.admin" % app)
+        except:
+            # Unregister the models that were registered in the last import as this import will have
+            # to reoccur on the next request and this would raise AlreadyRegistered exceptions (see #8245).
+            for model, admin_class in site._registry.items():
+                if model not in models_registered_before_import:
+                    site.unregister(model)
+            raise