If you have issues with your "Send-To-Messenger" buttons, generally there is only a single reason why. It's a minor issues, but it can be overlooked when you're setting up your application. Inside the guide we showed you the oAuth urls to insert and if you missed the subdomain for the buttons, that's the issue.
Let's get to the root of the issue ...
- Login to Facebook Developers portal ( http://developers.facebook.com/apps )
- Click on Facebook Login settings
- Scroll to Valid OAuth redirect URIs
If you're urls look like the above, you're issue is the urls. All you need to do in order to fix the issue is add http://btn.socialresponder.io and http://btn.socialresponder.io/optin into the box.
If all that information is correct and functional, then please continue with this article.
Check Webhook Settings - If you failed to sync the webhook, you will also cuase this error to exist, that's why it's extremely important to follow the information outlined in our videos, training and setup guides.