Facebook has decided to shut down Facebook Messenger for Windows desktop and Firefox on March 3. The messenger was released just last year.
The official Facebook messenger is now available for Android and iOS only.
This message is now appearing at the top of the app:
“We're sorry, but we can no longer support Facebook Messenger for Windows, and it will stop working on March 3, 2014. We really appreciate you using Messenger to reach your friends, and we want to make sure you know that you can keep chatting and view all your messages on http://www.facebook.com.”