We are sorry to announce that Facebook will put down their Facebook XMPP Chat API in April 30th 2015. For official Facebook information please see here. Key information quoted from there:
On April 30, 2014, we announced the deprecation of the XMPP Chat API as part of the release of Platform API v2.0. The service and API this document covers will no longer be available after April 30, 2015.
Once version 1.0 is deprecated on April 30, 2015, chat.facebook.com and the xmpp_login permission will no longer be available.
We will turn off our Facebook transport in the days after April 30th 2015. All data will be deleted. But you have to make sure that you clean up your roster and remove all @facebook.jabber.hot-chilli.net contacts.