Hi, it's a fake update designed to infect you with malware which we have seen a lot of in recent months! You should NEVER EVER click on anything like that! Please see the article - [[I found a fake Firefox update]]. If you are in any doubt about the authenticity of update pop-ups etc., it's always best to ignore them and check for genuine updates 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]]. We are trying to find a permanent fix, but it's proving very difficult. A possible workaround which seems to be quite effective, is to install an ad-blocker, such as - https://addons.mozilla.org/en-US/firefox/addon/ublock-origin Or, but this may be less effective - https://addons.mozilla.org/en-US/firefox/addon/adblock-plus '''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 you didn't run it, and everything works as usual, you should be OK, but if you think you have been infected, you can try these free programs to scan for malware, which work with your existing antivirus software: * [http://www.microsoft.com/security/scanner/default.aspx Microsoft Safety Scanner] * [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware] * [http://support.kaspersky.com/viruses/disinfection/5350 Anti-Rootkit Utility - TDSSKiller] * [http://general-changelog-team.fr/en/downloads/viewdownload/20-outils-de-xplode/2-adwcleaner AdwCleaner] (for more info, see this [http://www.bleepingcomputer.com/download/adwcleaner/ alternate AdwCleaner download page]) * [http://www.surfright.nl/en/hitmanpro/ Hitman Pro] * [http://www.eset.com/us/online-scanner/ ESET Online Scanner] [https://support.microsoft.com/help/14210/security-essentials-download Microsoft Security Essentials] is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection [https://www.microsoft.com/windows/windows-defender built-in]. Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. Did this fix your problems? Please report back to us. Thank you!