Recently we’ve received many questions from users whose Facebook Chat accounts will no longer connect in Instantbird.
Facebook officially deprecated its XMPP gateway on April 30th, 2015, but it continued to function until recently. Unfortunately it appears this is no longer the case.
After investigating the issue, we have been unable to find a workaround to keep it working. However, since Facebook deprecated the gateway, it’s surprising it even worked for this long!
Meanwhile, libpurple has a new protocol plugin that uses Facebook’s proprietary chat API, which we are considering offering as part of a future release of Instantbird.