Receiving 400 error code from facebook

Hello,

I’m using version 3.2.2 of rasa open source for facebook chatbot. I’ve linked facebook page and rasa and able to received messages from facebook. But rasa does not send message to facebook. I’ve debugged and found the following error. I’ve removed access token for security purpose. https://graph.facebook.com:443 “POST /v2.12/me/messages?access_token=EAAhci … HTTP/1.1” 400

I don’t know why it is happening. Is there anything else to check this issue?

BR,