https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar. How many profiles are listed? How many should be there? Also, open the profile folder in your file explorer.
+++++++++++++++++++++++++++++++++++++++++
Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Now in the Reply Box on the forum page, do a right-click in the box and select Paste.

If the data is too big, do not worry. It's the top part we need to look at.

This will show us your system details. No Personal Information Is Collected.

Hey FredMCD,

The application doesn't run and as such i cannot type in the about:profiles or support.

In /Library//application support, nothing exists because i've whiped Firefox in an attempt to start fresh. but despite the 'clean' install I still get the profile missing error

Is there a manual way I can get you the data you need?

I called for more help

Hey FredMcD, any luck?

Firefox uses two locations for the Firefox profile folder, so make sure to look in the correct location. Location used for the main profile that keeps your personal data (Root Directory on about:profiles).

• ~/Library/Application Support/Firefox/Profiles/<profile>/

Location used for the disk cache and other temporary files (Local Directory on about:profiles).

• ~/Library/Caches/Firefox/Profiles/

You can check the permissions (write/read and owner) of the profile folder and its files.

In Mac OS X v10.7 and later, the "~/Library" folder in the Home directory is a hidden folder.

• https://www.macworld.co.uk/how-to/mac-software/hidden-files-mac-3520878/

You can try to create a new profile.

See "Creating a profile":

• https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Hey cor-el

Thanks for your response. Reinstalled Firefox via 76.0.1. Profile missing error still pops up on initial execution. Application then does not run.

Results below:

~/Library/Application Support/Firefox/Profiles/<profile>/

Does not exist. ~/Library/Application Support/Firefox <- is empty.

~/Library/Caches/Firefox/Profiles/

Does not exist. ~/Library/Caches is a blank text file.

I cannot use any of the 'create new profile' tips becasue firefox does not run.

Try to reinstall Firefox.

Download the full version of the current release and trash the currently installed Firefox application to do a clean reinstall.

Download a new copy of the Firefox application and save the Disk Image file to the desktop Firefox 58.0.2:

   https://www.mozilla.org/en-US/firefox/all/ 

   trash the currently installed Firefox application (open the Applications folder in the Finder and drag the Firefox application to the Trash) to do a clean reinstall
   install the new version that you have downloaded
   https://support.mozilla.org/en-US/kb/Installing+Firefox+on+Mac 

Your personal data like bookmarks is stored in the Firefox profile folder, so you won't lose personal data When you uninstall and 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.

See also:

   https://appletoolbox.com/2016/07/fix-corrupt-user-accounts-macos/ 

Partisanpixel Partisanpixel Question owner 3/15/18, 6:04 AM

Thanks FredMcD, Cor-el and AMAN,

Unfortunately a few variables changed so i cannot pin point the exact solution however I will inform you what changed.

1. Used Aman's apple tool box link to book into safemode and delete the Library/Caches text file (it wasn't a folder)
2. I also used safe mode and went to Library/Preferences and deleted ZoomChat.plist (it was around that time that this issued showed up. unsure if this meant anything whatsoever.
3. Installed a fresh Firefox 77.0.1.dmg.
4. Firefox runs.

Note I had troubleshooted by making a new 'test' admin account which installed 77.0.1 just fine and ran firefox without issue before i went through the above 1-4.

Thanks again all.