Make sure you are not blocking content. https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop also see https://blog.mozilla.org/security/2021/03/23/introducing-smartblock/ https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection --------------- [https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode Diagnose Firefox issues using Troubleshoot(Safe) Mode] {web link} A small dialog should appear. Click '''Start In Troubleshoot(Safe) Mode''' (not Refresh). Is the problem still there? Many site issues can be caused by corrupt cookies or cache. '''Warning ! ! ''' This will log you out of sites you're logged in to. You may also lose any settings for that website. * [https://support.mozilla.org/en-US/kb/delete-cookies-remove-info-websites-stored Delete cookies to remove the information websites have stored on your computer] {web link} * [https://support.mozilla.org/en-US/kb/how-clear-firefox-cache How to clear the Firefox cache] {web link}

Similar problem here. FedEx login not possible on Firefox. No issues on MS Edge. I've tried all the usual "fixes," but there are simply some websites that routinely do not work with Firefox.

Some websites just don't like Firefox. Some users have gone as far as changing their User-Agent to get those sites to work. (Are they jealous perhaps?) I have several versions of Firefox and had no problem. There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own. https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites https://support.mozilla.org/en-US/kb/secure-connection-failed-firefox-did-not-connect https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors [https://support.mozilla.org/en-US/kb/what-does-your-connection-is-not-secure-mean What do the security warning codes mean]

Also please check out: https://support.mozilla.org/en-US/questions/1364032#answer-1475084