I am unable to add Facebook Messenger as a channel to my bot. I'm receiving 400 error in the console and a fairly arcane error message (see the attached image). I have been able to successfully add DirectLine, Skype, and Slack.
From a troubleshooting perspective, I've tried the following:
Any help would be much appreciated.
I discovered the root issue here. The person who created the Facebook App did not associated it with a Facebook Page and generate the requisite Page Access Token. Once this was completed adding the Facebook Messenger channel worked correctly.
Thanks for pointing me in the right direction Bob Swager!