FWIW, I googled "Mozilla default release", because I know that newer installs of FF include a profile with that name.

I had deleted the one that appeared when I now recently did a fresh install of FF, and I'm wondering if that contributes in any way to my problem.

I found this thread: https://support.mozilla.org/en-US/questions/1259820#:~:text=under%20%22Start%20the%20Profile%20Manager%20when%20Firefox%20is,that%27ll%20take%20you%20back%20to%20your%20old%20profile.

Could this thread have any bearing on my problem? (fyi, I don't see any "compatibility.ini" file in my profile files; only a "compatibility" file.)

Hi blue_sky, you aren't limited to using the default profile names.

By default, Windows hides many file extensions. To be able to see those, you can turn off the hiding. This article has the steps: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

On the larger question of why your profile only works on the first try, it's a bit of a mystery. Over the years there have been some features that are off in a new profile and that Firefox turns on during the first run. But it's difficult to remember them at this late hour.

Will Firefox start in the "default" profile in its Safe Mode? Firefox's Safe Mode temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help button > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Hi, Wow! (You're a magic fount of knowledge!  : ) )

Yes, I pressed Shift while starting FF -- and then was able to start in safe mode -- and the browser did open using the restored profile ("bxfz7tby.default" )!!

So the question is what do I do next?

While I was in the browser, I disabled ALL the extensions (there were 9), closed out of FF, and then tried reopening it the regular way.

It did not open successfully. Instead I got the image below on trying to reopen: "<toolbarbutton id="UITourTool tipClose" class="close-icon". </p>

So for the moment, I am able to get back into the FF browser -- but only in Safe Mode.

Your suggestions?

Hi blue_sky, you aren't limited to using the default profile names. By default, Windows hides many file extensions. To be able to see those, you can turn off the hiding. This article has the steps: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

Oh, I had thought my file extensions were showing, since some did show. But you were right, I had not checked to show them. I checked it and now I do see compatibility.ini.

So do you think I should try deleting that folder? Or, is there some better direction to take, now that I've at least been able to get into FF using Safe Mode?

One other important difference in Firefox's Safe Mode is that hardware acceleration is disabled. This is a potential workaround for incompatibilities between Firefox and your graphics card/chipset driver software. This article describes where to make that change: Firefox's performance settings. That will take effect the next time you exit Firefox and start it up again in normal mode. Any difference?

Since hardware acceleration improves the appearance of fonts and animations, you may want to check whether graphics card/chipset driver updates are available for your system. This article suggests safe ways to do that: Upgrade your graphics drivers to use hardware acceleration and WebGL.

Wow, this is very complicated to resolve!

So I have not yet looked into updating my graphics card or chipset. (Theoretically that could be a contributing issue, since after my Fresh Start install of Windows, it's possible some of my drivers got changed. FWIW though, Chrome and Edge seem to be working ok.)

So I did try your suggestion in that I both unchecked "Use hardware acceleration when available" and I disabled webgl. But when I tried opening FF, I got same message:

"<toolbarbutton .="" <="" class="close-icon" id="UITourTool tipClose" p=""></toolbarbutton>

So I googled that, and found this ("Firefox is not opening correctly"): https://support.mozilla.org/en-US/questions/1295475

Do you think the issue could be my version of FF and that I should uninstall and reinstall differently? I had downloaded the version of FF I have from Ninite, rather than from Mozilla. This is the version information in my FF About page:

79.0 Firefox Release

July 28, 2020 Version 79.0, first offered to Release channel users on July 28, 2020

We'd like to extend a special thank you to all of the new Mozillians who contributed to this release of Firefox. New

   We’ve rolled out WebRender to more Windows users with Intel and AMD GPUs, bringing improved graphics performance to an even larger audience.

Do a clean reinstall of the current Firefox release and delete the Firefox program folder before installing a fresh copy of the current Firefox release.

• download the Firefox installer and save the file to the desktop
  *https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

If possible uninstall your current Firefox version to cleanup the Windows Registry and settings in security software.

• do NOT remove "personal data" when you uninstall the current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including personal data in profiles created by other Firefox versions

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

• it is important to delete the Firefox program folder to remove all the files and make sure there are no problems with files that were leftover after uninstalling

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data when you reinstall or update Firefox, but make sure NOT to remove personal data when you uninstall Firefox as that will remove all Firefox profile folders and you lose your personal data.

If you keep having problems then you can create a new profile as a quick test to see if your current profile is causing the problem.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Reinstall Firefox

• https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems

@cor-el,

Hi, Thank you for this! I'm just a little confused about the order in which to do what you recommended.

Is this the correct order? . . .

1) Go to Add/Remove Programs and uninstall Firefox 2) Go to ""C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Firefox.lnk"" and delete "Firefox.Ink" from within Programs 3) download and install FF directly from Mozilla using the link you provided [Use 64-bit version since my Windows 10 is 64-bit]

In regard to your suggestion, "cleanup the Windows Registry and settings in security software." -- how would I do that? Should I uninstall using Revo uninstaller, instead of Add/Remove, so that Revo can clean up Registry . . .?

Also, I'm not clear about what "settings in security software" I should clean up, or how to do so.

The second step is not about removing the .LNK file, but about checking the Firefox installation folder and make sure no files are leftover after uninstalling Firefox.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

ok, I see. and is there a recommended way for uninstalling? or should I just do it via Settings > Apps > Apps & Features > select Firefox and Uninstall?

Yes, with uninstalling is meant to uninstall Firefox via the Windows Control Panel. That way the Firefox uninstaller is run and ensures that the Windows Registry gets updated properly.

The second step is not about removing the .LNK file, but about checking the Firefox installation folder and make sure no files are leftover after uninstalling Firefox.

• (64-bit Firefox) "C:\Program Files\Mozilla Firefox\"
• (32-bit Firefox) "C:\Program Files (x86)\Mozilla Firefox\"

Ok, I downloaded the program from your link, (the plain 64-bit "Firefox" release) and saved to desktop. I uninstalled my current FF using Control Panel. I eyeballed both paths above and the only "Mozilla" anything I show is "C:\Program Files (x86)\Mozilla Maintenance Service". I assume I can leave that alone?

If so, now I should proceed to click on the Firefox Setup 79.0 exe file I saved to desktop?

Yes, there is no need to remove the Mozilla Maintenance Service.

You can proceed to install Firefox 79 by running the "Firefox Setup 79.0.exe" file.

I installed Firefox 79 by running the "Firefox Setup 79.0.exe" file, and when I clicked "Finish" to open the program, I once again got the image with message: "<toolbarbutton .="" <="" class="close-icon" id="UITourTool tipClose" p=""></toolbarbutton>

I can only open the profile in Safe Mode.

What would you all suggest next?

Should I try Refresh Firefox on that profile? If I do, will it only remove my extensions and add-ons? (I don't mind it removing those, since I have a list of them and can always reinstall them. But I just want to make sure I'll retain all my bookmarks, browsing history, open tabs, etc.)

Does Firefox work properly with a new profile ?

If that is the case then this old profile is broken and not compatible and best is to use as less files as possible from the old profile.

You didn't restore the profile in the "AppData\Local" location as that includes the startup cache and can likely cause problems?

You can try to clear the startup cache in Firefox 79 and newer via the "Help -> Troubleshooting Information" (about:support) page.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

Does Firefox work properly with a new profile ? If that is the case then this old profile is broken and not compatible and best is to use as less files as possible from the old profile. You didn't restore the profile in the "AppData\Local" location as that includes the startup cache and can likely cause problems? You can try to clear the startup cache in Firefox 79 and newer via the "Help -> Troubleshooting Information" (about:support) page.

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

The new profile does seem to work ok -- although unlike the old profile, it doesn't have any extensions added to it. Also, since the restored profile is the one now set as default, the way I open the new profile is by opening FF (the restored profile) in Safe Mode, and then going to About:Profiles and launching the newer profile from there.

In answer to your question, Yes, in fact when I restored the old profile, I restored both the Mozilla AppData\Roaming profile folder and the corresponding Mozilla AppData\Local profile folder.

Should I have only restored the Roaming profile folder?? Should I delete the restored profile's AppData\Local folder and try again?'

(I really want to find a way to salvage the restored profile because it has hundreds of organized, bookmarked pages collected over years of use. It'd be a big loss to forfeit that and start from scratch.)

AT LAST!!!

So I think I've finally gotten my problem resolved!!

In all my earlier attempts at restoring my profile, I had pasted back both my "AppData\Local" and "AppData\Roaming" Mozilla FF folders when I tried restoring my backed up FF profile. I've no idea if this had contributed to my original problem or not.

However, and FWIW, I did try a new FF install -- this time only restoring the "AppData\Roaming" folder -- but I still ended up not being able to successfully open the profile a second time.

I suspect that the culprit to all my problems may have been some of my Add-on extensions in the restored profile.

So finally, I went into Safe Mode and while there did a Refresh Firefox.

That introduced a new file name to my profile. Whereas before the file name had been formatted as "xxxxxx.default", after the refresh, the file name was now formatted as "yyyyyyy.default-#######

And in fact, once I did the Refresh Firefox, since then I have successfully been able to repeatedly open to my restored profile by simply clicking on Firefox!

[I was concerned that once I signed into my FF account again, that sync -- which had been set to also sync my add-ons -- might re-introduce problematic add-ons.

Luckily, I found this (https://support.mozilla.org/en-US/questions/1287277) archived post and solution from you, cor-el, and that allowed me to turn off syncing of Add-ons before I signed in. ]

So kudos and great thanks to both @jscher2000 and @cor-el for so patiently sticking with me and helping me to troubleshoot to success!!

Now, one more thing:

So in my newly restored, working FF profile, I have Add-Ons unchecked in syncing, because I wanted to be sure that Add-Ons from my previous FF incarnation would not conflict with this new, version 79 profile.

However, I am concerned that at some future point I might forget why I had disabled Add-ons in sync, and that if I check it and do a sync, it might re-introduce the old Add-ons.

So what I want to do now is to delete all the old Add-ons (essentially from the Sync server) . . . if they are still there.

What is the safest way to do that?

Would it work if I did the following?

- Open FF (my current working restored profile) -- but open it in Safe Mode. - check Add-ons in sync - allow sync - if the Add-ons show up, delete them