{ "error": { "message": "An unknown error has occurred.", "type": "OAuthException", "code": 1, "fbtrace_id": "randomcode here" } } Solutions: visit: https://developers.facebook.com/tools/explorer

User or Page Options or dropdown of "User or Page"

then Select your page then copy token if not expired donot generate new remember just copy token and use will fix issue if not fixed then new working token will be given in 3 to 4 hours if same issue again came

issue because came you was not using page token but default it gave you id token of facebook which not needed so when you selected page from "User or Page" you will see changed token and use this one use and follow this payload

body raw json {"recipient":{"id":"id_of_which_u_want_send_message"},"messaging_type":"RESPONSE","message":{"text":"Hello, World!"},

Headers Content-Type application/json

Parameter link use this https://graph.facebook.com/v13.0/messenger id of u gave token/messages?access_token=ur_token_here

Assuming u using postman