Do you possibly have ESET security software as that software has been reported to cause such issues with extensions ?

I do have eset, and that's the 1st suggestion somebody gave me, disable it temporarily while downloading and installing FF. i tried it 3 times. 3TIMES! I also deleted every single file as was suggested; username\AppData\Roaming\Mozilla username\AppData\Local\Mozilla [HKEY_CLASSES_ROOT\FirefoxHTML]

[HKEY_CLASSES_ROOT\FirefoxURL\]

[HKEY_CURRENT_USER\Software\Mozilla]

[HKEY_CURRENT_USER\Software\MozillaPlugins]

[HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla]

[HKEY_LOCAL_MACHINE\SOFTWARE\mozilla.org]

[HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mozilla]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\mozilla.org]

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\MozillaPlugins]

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\FirefoxHTML]

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\FirefoxURL]

I even found another entry to delete, rebooted disabled eset, downloaded FF. Sometimes it says I see you already DL FF, let's get you a fresh copy, or it installs fine, but can't install corrupt addons or themes. I also did the "troubleshoot-delete the 4 entries thing", but it didn't work. Nothing has helped.

All the extensions worked in chrome. (and waterfox) Why not Firefox? Why? I think this version is bugged. They work for some pc configurations, but not others. I've never had a problem with FF, but I'm ready to kick it to the curb if I can't fix the dam thing.

Can you download an extension from the Add-ons website by right-clicking the blue "Add to Firefox" button if you boot the computer in Windows Safe mode ?

Boot the computer in Windows Safe Mode with network support to see if that has effect.

• https://www.bleepingcomputer.com/tuto.../how-to-start-windows-in-safe-mode/
• https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/

You can check for problems with the extensions registry files in the profile folder.

Try to reset the extensions registry and rename extensions.json (extensionsOLD.json) and rename/remove compatibility.ini in the Firefox profile folder with Firefox closed.

• https://support.mozilla.org/en-US/kb/Profiles

New files will be created when required.

See "corrupt extension files":

• https://support.mozilla.org/en-US/kb/unable-install-add-ons-extensions-or-themes

You can check for possible updates in case of issues.

• click the cogwheel (left of the Search bar) on the about:addons page to "Check for updates"

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

Yay! It worked! I went into safe mode and got my addons and a theme i like, restarted, and they work! I so happy, thank you very very much for your time and effort! My only other "thing" about FF is their data mining, which i know happens. even though we disable it, it's just for show.

i been using waterfox, but a corp bought them, all the browsers do this, with tor being pretty much the exception. Like they say, if it's free, you ARE the product. Thanks again, cor-el! I really, really appreciate it! I didn't rename anything, they just work, Ima leave well enough alone.