diff --git a/src/langbot/libs/dify_service_api/v1/client.py b/src/langbot/libs/dify_service_api/v1/client.py
index cc8008e1..bc0ee8fa 100644
--- a/src/langbot/libs/dify_service_api/v1/client.py
+++ b/src/langbot/libs/dify_service_api/v1/client.py
@@ -145,7 +145,7 @@ class AsyncDifyServiceClient:
                     'file': file,
                 },
                 data={
-                    'user': (None, user),
+                    'user': user,
                 },
             )