Refused to display….. frame-ancestors https://www.facebook.com

There are two things required to avoid this message:

1. Ensure you have the correct Facebook page ID set in your HTML. This should be the numeric ID, not what you see in the URL. I found my page’s numeric ID via https://findmyfbid.com

   Example:

   <div class="fb-customerchat" page_id="6708927376315932">
   </div>
   

2. Whitelist your domain at Your Page > Settings > Messenger Platform. Ensure this matches your domain, uses HTTPS protocol, and include the port too if using a non-standard port.
   (And then make sure you hit the Save button!)