Does this work better if you try to login here?

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

Thanks for responding. I've tried both of your suggestions, and it made no difference - I'm still prompted to enter an access code from an email that was not delivered. I've tried this multiple times with multiple devices, including using the webmail site of my ISP (rather than Outlook), and I see no evidence of any access code emails from Mozilla.

dood Firefox turned everything in particularly my "profile" folder. It turned that SOB inside and out and without warning. I mean expect changes due to the fact I run Nightly and have a customized autoconfig to run userscripts and I use chrome folder to change...i mean "tweak" firefox UI especially fighting this new one has been a PIA, I dont hate everything, in fact I like a lot and I think they did a rather good job however I wish they would sometimes pause for a moment and realize that I'd imagine even people who don't super customize their firefox don't take too kindly to forced changes that result in breakage, For example tons of people probably enjoy either the vertical tabs or bar, not me, I like my setup that has the sidebar auto expand on hover. To Mozilla credit I have been able thus far to keep a lot of the changes off, especially the sneaky abd seems ever more present advertising and tracking & pinging added to new updates without notice and if you are or a nerd how would you ever know what could really be going on. Im all for change dont get me wrong, however I think allowing users to have a choice to not change especially on big changes would be a good idea. EX forcing people to adapt to a vertical tab bar and then in probably less than a year, or however long a design cycle for you guys are, they are forced to change yet again. Lastly before i get back on topic, remember Firefox is a good looking and running browser. No need to overdo it with the visuals. I think the move there is create options for users to change their setup kinda like some firefox userchrome themes-pick type tabs, hover color, selected color etc and that way advanced users cans still tweak away and people who just want to open and browse-works for both! And more time for devs to do more productive stuff and you know this what get users all up in arm with pitch fork---->design changes.

Yah so my mozilla support folder containing all my profiles is such a mess and in disarray! I found out that I actually have separate profiles that are linked and thus i can delete them! Good thing is though if one is logged in which chances are good., I dealt with same problem. What you can do is copy the profile you want to use-use tool-profile manager and then just select your profile and copy.. It will create an exact profile folder just with different name, I changed settings in about:config to something like profiles.allow danger merge and profiles new names...dunno just tried things bc it was frustrating. If you dont have profiles showing in menu bar or top bar go to about:profiles and you can set a default or open other profiles etc. Open the open you created the copy it should want to sync if not try closing old profile if its open and try closing window and opening new window and then try to sync to your normal mozilla account. These 2 profiles wll probably be linked. If still not working try opening profile in troubleshoot mode-just dont click the refresh profile-it will wipe//delete everything.Totally fine press restart in troubleshoot and see if you can sync. Keep playing with it you can do it. Worst comes to worst create a new mozilla acct but that last resort. If you can login why? does it say another profile is logged in? log him out hah. Once you have it setup you can decide what profile you want to use because both will be the same and linked.. Go to about:profiles and select a default profile. Also you can enable profile dont know code for about:config and it will have your profiles listed up top on menu bar easy ti scroll from titlebar menu and a menu in the right side setting menu.e

Good luck if you have problems respond back and try help you

i think you can use your backupcodes to confirm or passkey to skip. Aslo if still no luck try forgot password and go from there