iCloud Password doesn't work properly

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

Yes, I have, but it didn't help.

I would try removing your login info from keychain, reboot, and try again.

I'm having this issue too. I don't know what caused it. I literally reinstalled it all and used the Icloud install extension, via the icloud app on windows, and nothing. and it still gives me this.

This happened on a recent update too... I wish there was a way to go back on there because the updates end up being more of a breaking things vs fixing things...

What can be done to get this corrected?