I don't know how this would happen but I would just advise for you to reset your password and see if the problem still persits. I know this is a hastle but I can't think of any other way.

If you use extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) that can block content (Adblock Plus, NoScript, Disconnect, Ghostery, Privacy Badger, uBlock Origin) always make sure such extensions do not block content.

• make sure your extensions and filters are updated to the latest version
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Firefox shows a purple shield instead of a gray shield at the left end of the location/address bar in case Enhanced Tracking Protection is blocking content. You can click shield icon for more detail and possibly disable the protection. You can check the Web Console for messages about blocked content.

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

Can you login to the Firefox account via this web page?

• https://accounts.firefox.com/signin
• https://accounts.firefox.com/settings

Okay so it gets stranger. Today I used my main machine as usual. I read the email with the above responses and then turned on the problem machine ready to try the things you listed above. Incredibly when I started Firefox on the problem machine, it was immediately apparent that I was logged in. I did not have to enter my email address or password. So strange. Yesterday I did try things like starting up and shutting down Firefox multiple times, rebooting multiple times, full power off multiple times, yet none of these actions made any difference. Today I do nothing and I am logged in, how weird is that ?

On another subject, a couple years ago I posted a question on this forum. Last night while on this forum I looked at that post again and realized that some how I missed the response that you core-el had posted. Last night I followed your instructions and created a gtk.css and now my scroll bar problem is fixed. THANK-YOU VERY MUCH ! Thank-you for that solution and for all the help you provide to others.

Ignore everything I said in the first paragraph above. The problem persists. I am using the "problem machine" to learn Python. If deisred, I can swap out hard drives on that machine. So what I did yesterday was remove a drive, put in a different drive (which I will refer to as the new drive) and installed Ubuntu 20.04 from scratch so I could have blank slate to work on. This is the drive that is giving me the problems. This morning, pre-caffeine, I turned that machine on forgetting that last night I had put the old hard drive back into the machine to do a little pythoning before going to sleep. When I realized my mistake I swapped drives and the problem persists on the new drive.

I am able to log into my google and yahoo email account with no difficulty with the new drive but still not able to login to Firefox.

I have no extensions or filters installed as I rely on Firefox to install those when I login and I am unable to login. The shield is grey.

As a further check to make sure it's not a typo on my part, I used the "logins and passwords" in Firefox on this machine and copied my email and password and pasted those into a text file and sent the file to the problem machine, then I copied and pasted from the text file to the login page and still failed.

In order to eliminate Firefox as the problem, I installed the Chromium browser and login failed there as well.

I am perplexed!