diff --git a/api/controllers/service_api/dataset/rag_pipeline/rag_pipeline_workflow.py b/api/controllers/service_api/dataset/rag_pipeline/rag_pipeline_workflow.py
index ad578d947e..cbc1907bf5 100644
--- a/api/controllers/service_api/dataset/rag_pipeline/rag_pipeline_workflow.py
+++ b/api/controllers/service_api/dataset/rag_pipeline/rag_pipeline_workflow.py
@@ -214,7 +214,7 @@ class KnowledgebasePipelineFileUploadApi(DatasetApiResource):
             raise UnsupportedFileTypeError()
 
         if not file.filename:
-            raise FilenameNotExistsError+
+            raise FilenameNotExistsError
         
         if not current_user:
             raise ValueError("Invalid user account")