Hi, we are getting a lot of reports like yours of late - it's a scam designed to infect you with malware! NEVER EVER click on anything like that. If you are in any doubt about the authenticity of update pop-ups etc., it's always best to ignore them and check for yourself by opening 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 version]]. A possible workaround is to install an ad-blocker, such as - https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/?src=ss Or https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/?src=ss '''For reference only - please don't post here - this forum is for Mozilla Support Contributors only''' https://support.mozilla.org/en-US/forums/contributors/712056?last=69507 ''If your question is resolved by this or another answer, please take a minute to let us know. Thank you.''