What OS? What version of Firefox? Did you try with Firefox in Troubleshoot Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf Did you clear your browser cache? https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox Clear Startup Cache. see screenshot

It is possible that your firewall or other security software blocks or restricts Firefox after detecting that Firefox updated. Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full access for all Firefox processes. See: *https://support.mozilla.org/en-US/kb/server-not-found-connection-problem *https://support.mozilla.org/en-US/kb/Firewalls *https://support.mozilla.org/en-US/kb/fix-problems-connecting-websites-after-updating ---- Reboot the computer into Windows Safe Mode with network support to see if that has effect. *[https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/] *[https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/]