Update app.py

let's see?

app.py

@@ -30,7 +30,7 @@ def factory():
 async def main(message):
     llm_chain = cl.user_session.get("llm_chain")
 
-    res = await llm_chain.acall(message, callbacks=[cl.AsyncLangchainCallbackHandler()])
+    res = await llm_chain.acall(message.content, callbacks=[cl.AsyncLangchainCallbackHandler()])
 
     await cl.Message(content=res["text"]).send()