As already noticed here, the Facebook XMPP chat API is deprecated starting on April 30, 2015.
After April 30th, 2015 apps will no longer be able to access the
service or API. This includes both access to chat.facebook.com and the
You could, since 2010, add your facebook chat account to any XMPP client. This incluided but not limited to Pidgin and Emphaty, the previous and current IM default client on the main Ubuntu desktop.
At the current time I'm writting this my facebook account set up in pidgin is still working, however I ignore the current status of trying to set up a new account.
As part of the announce from Facebook and after the API officialy deprecated, the latest Empathy security update removed Facebook chat from the recommended protocols.
empathy (3.8.6-0ubuntu9.2) trusty; urgency=medium
[ Alberto Mardegan ] * debian/control:
- Remove WLM and Facebook plugins from Recommends (LP: #1432613)
- Remove WLM and Facebook from package descriptions.
Instructions to add the Facebook chat to Pidgin (should work for any XMPP client.)