Have you tried Firefox in Safe Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode Also try clear the browser cache. https://support.mozilla.org/en-US/kb/how-clear-firefox-cache What's showing for you in the section showing of my screenshot? What security software are you running? What happens when you try login.live.com and then try to access onedrive?

I cleared the cashed stuff, but when trying to log in, I get (after quite a while) https://onedrive.live.com/?gologin=1&wt.mc_id=product_officelive_home&auth=1 which is a blank page.... Until yesterday I never had a problem and any other browser just lets me log in.

Tried the safe mode and get same problem. Going via login.live.com is easy and can open anything there except OneDrive :(

Interesting... several other users are having the same issue. What security software are you running?

Surfshark VPN and standard Windows Defender stuff.

Have you already tried disabling Surfshark and rebooting to see if it makes a difference?

Yes I have tried that as well with unfortunately no success :( I'm getting the feeling that my Firefox days are over and will have to revert to Chrome or Edge. Unless someone here can still come up with a brilliant idea.

Oh stop being so dramatic. LMAO Just for S&Gs try another version and see what happens. https://www.mozilla.org/en-US/firefox/all/#product-desktop-release Also update to the new version 101.0. May the Schwartz be with you...

Well, now I uninstalled Firefox, downloaded latest version, rebooted after uninstall, installed that latest version, get prompted for my OneDrive password, takes a long time, and comes up with a blank page. Great stuff.

You can try these steps in case of issues with webpages:

You can reload webpage(s) and bypass the cache to refresh possibly outdated or corrupted files.

• hold down the Shift key and left-click the Reload button
• press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• press "Command + Shift + R" (Mac)

Clear the Cache and remove the Cookies for websites that cause problems via the "3-bar" Firefox menu button (Settings).

"Remove the Cookies" for websites that cause problems:

• Settings -> Privacy & Security
  Cookies and Site Data: "Manage Data"

"Clear the Cache":

• Settings -> Privacy & Security
  Cookies and Site Data -> Clear Data -> [X] Cached Web Content -> Clear

• https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox
• https://support.mozilla.org/en-US/kb/how-clear-firefox-cache

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

• https://support.mozilla.org/en-US/kb/enhanced-tracking-protection-firefox-desktop
• https://support.mozilla.org/en-US/kb/smartblock-enhanced-tracking-protection
• https://support.mozilla.org/en-US/kb/trackers-and-scripts-firefox-blocks-enhanced-track

If clearing cookies doesn't help then it is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and when present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

You can use the button on the "Help -> More Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page (Root directory).

• Help -> More Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Thank you very much for all the assistance/replies. Problem now solved.