diff --git a/backend/app/rag/chat.py b/backend/app/rag/chat.py
index 5b789049..c12820d8 100644
--- a/backend/app/rag/chat.py
+++ b/backend/app/rag/chat.py
@@ -875,6 +875,7 @@ def _external_chat(self) -> Generator[ChatEvent | str, None, None]:
             chat_params = {
                 "goal": goal,
                 "response_format": response_format,
+                "namespace_name": "Default",
             }
             res = requests.post(stream_chat_api_url, json=chat_params, stream=True)