Hi, since the message is coming from FB, you would need to contact them for advice, but as you are using a very old version of Firefox, they will probably tell you that such an old one is no longer supported.

I know that for whatever reason you don't want to update, but if you change your mind, open the 3-bar menu > Help (question mark at bottom right) > About Firefox. Alternatively, you can press the Alt key to bring up the main menu bar > Help > About Firefox. More - Update Firefox to the latest release.

The only alternative is to try another browser for that site.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!

Come on what kind of support center is this i mean no offense but i have removed this message in the past i just dont remember it now Help is highly appreciated ....!!!!

The message is on the Facebook site due to you still using the old Firefox 31.0 as this is not a message from Mozilla or the Firefox web browser.

Not sure if you can turn such notifications off on the Facebook site as i use FB very little.