diff --git a/cms/djangoapps/contentstore/tasks.py b/cms/djangoapps/contentstore/tasks.py
index fc588065cf..e36a8edae8 100644
--- a/cms/djangoapps/contentstore/tasks.py
+++ b/cms/djangoapps/contentstore/tasks.py
@@ -1375,7 +1375,7 @@ def _filter_by_status(results):
             continue
         elif status == 403 and _is_studio_url(url):
             filtered_results.append([block_id, url, LinkState.LOCKED])
-        elif status in [403, None] and not _is_studio_url(url):
+        elif status in [403, 500, None] and not _is_studio_url(url):
             filtered_results.append([block_id, url, LinkState.EXTERNAL_FORBIDDEN])
         else:
             filtered_results.append([block_id, url, LinkState.BROKEN])
diff --git a/openedx/core/djangoapps/notifications/admin.py b/openedx/core/djangoapps/notifications/admin.py
index 82524e4b08..a57d3458e9 100644
--- a/openedx/core/djangoapps/notifications/admin.py
+++ b/openedx/core/djangoapps/notifications/admin.py
@@ -82,6 +82,10 @@ class CourseNotificationPreferenceAdmin(admin.ModelAdmin):
     def get_username(self, obj):
         return obj.user.username
 
+    def get_queryset(self, request):
+        queryset = super().get_queryset(request)
+        return queryset.select_related("user").only("id", "user__username", "course_id")
+
     def get_search_results(self, request, queryset, search_term):
         """
         Custom search for CourseNotificationPreference model