message: try stringify request_body
diff: @@ -770,7 +770,7 @@ function Facebookbot(configuration) {
  };
  console.log({request_body})
  request.post('https://' + api_host + '/v2.6/me/pass_thread_control?access_token=' + configuration.access_token,
  - request_body,
  + JSON.stringify(request_body),
  function(err, res, body) {
  if (err) {
  facebook_botkit.log('Could not pass thread control');
  