diff --git a/agent/component/message.py b/agent/component/message.py
index 555534610..36cee1422 100644
--- a/agent/component/message.py
+++ b/agent/component/message.py
@@ -177,6 +177,9 @@ class Message(ComponentBase):
 
     def _convert_content(self, content):
         doc_id = get_uuid()
+
+        if not self._param.output_format or not isinstance(self._param.output_format, str):
+            return
         
         if self._param.output_format.lower() not in {"markdown", "html", "pdf", "docx"}:
             self._param.output_format = "markdown"