Facebook messenger app webhook subscription - Insufficient Permission
I have facebook messenger application (it is bot using MS Bot Framework, although I don't think it is relevant). It has webhook subscribed to page events. It used to work fine until few days ago, when the webhook was unsubscribed from page and when I am trying to subscribe again it tells me:
"Insufficient Permission You do not have the necessary permission for the specified Page to perform the requested action."
I am owner and admin on both the FB page and messenger app. I created similar page and messenger app and it works there, but I still need to use this old one. I tried subscribing to other pages which I own and admin, but with same result. I also tried it with other person who is admin.
I found other people experiencing same/similar message on FB, but not in this particular case. But I haven't found any solution.
Does anyone know what could be the problem? Or have anyone experienced this issue?
Thanks in advance for any ideas.
Answer
You need to generate a token first. Under messager->Settings->Token Generation-> Select your page and you'll be prompted to give the permission. Grant all permission required, then you shall be able to subscribe or unsubscribe to pages you manage.
This process gives your application the token to validate if you have the moderator or higher rights to the page you want to subscribe to.