diff --git a/cocoa/tests_backend/app.py b/cocoa/tests_backend/app.py
index 31ff9ae92f..076274830a 100644
--- a/cocoa/tests_backend/app.py
+++ b/cocoa/tests_backend/app.py
@@ -64,11 +64,16 @@ def _menu_item(self, path):
             while True:
                 label, path = path[0], path[1:]
                 item = menu.itemWithTitle(label)
+                if item is None:
+                    raise AttributeError()
                 menu = item.submenu
         except IndexError:
             pass
         except AttributeError:
-            raise AssertionError(f"Menu {' > '.join(orig_path)} not found")
+            raise AssertionError(
+                f"Menu {' > '.join(orig_path)} not found; menu {menu.title} has items "
+                + ",".join(f"{item.title!r}" for item in menu.itemArray)
+            )
 
         return item