I had this problem until I realised I had blocked updates in Hosts to run an older version of FF. You are probably getting the message repeated because it's not actually downloaded and installed the update? This could be blocked in a firewall or AV software? What is your FF version and is it the latest? When I had this I didn't want to take the offline file and install it in case it reverted all my settings and addons back to vanilla - I still don't know if that would happen. My Windows 64 FF version is now 79.0 Also, I think FF keeps calling home to check your version even if it is the latest. If that request and reply to their server is blocked (Firewall?) the app keeps giving you that annoying drop down message since current version status isn't confirmed.