I believe i am having the same problem as this post (
https://stackideas.com/forums/400-error-when-submitting-to-facebook-replying-back-to-ticket-256513 )
I have linked the Facebook app and followed all the documentation, but i missed something. I can create a post, when i try to share it to Facebook, i get this error (400 Expected 1 '.' in the input between the postcard and the payload).
Could you look into this?