diff --git a/test/webapi/viewer/test_routes.py b/test/webapi/viewer/test_routes.py
index 298f8e1ca..3066e27af 100644
--- a/test/webapi/viewer/test_routes.py
+++ b/test/webapi/viewer/test_routes.py
@@ -141,7 +141,10 @@ def setUp(self) -> None:
 
     def test_viewer_ext_contributions(self):
         response = self.fetch("/viewer/ext/contributions")
-        self.assertResourceNotFoundResponse(response)
+        self.assertResponseOK(response)
+        self.assertEqual(
+            {"result": {"extensions": [], "contributions": {}}}, response.json()
+        )
 
     def test_viewer_ext_layout(self):
         response = self.fetch(
diff --git a/xcube/webapi/viewer/routes.py b/xcube/webapi/viewer/routes.py
index 40287be74..5357d988a 100644
--- a/xcube/webapi/viewer/routes.py
+++ b/xcube/webapi/viewer/routes.py
@@ -160,7 +160,9 @@ def new_key(self, length: int = 8) -> str:
 class ViewerExtHandler(ApiHandler[ViewerContext]):
     def do_get_contributions(self):
         if self.ctx.ext_ctx is None:
-            self._write_no_ext_status()
+            self._write_response(
+                ExtResponse.success({"extensions": [], "contributions": {}})
+            )
         else:
             self._write_response(get_contributions(self.ctx.ext_ctx))