See:

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

Thanks but I read that post before I posted mine. It provides instructions on how to run FF if you have moved, renamed, or deleted your FF profile folder. I have done none of these. I can see my existing profile folder but FF won't run. Related guides on refresh FF feature and FF troubleshoot mode are not useful as they assume FF is able to run.

Is there any way to fix this without using Terminal?

This is basically a problem with the profiles.ini file that registers profiles. You get this error when profiles.ini point Firefox to a profile that no longer is present on the hard drive. You can start Firefox with the -P parameter to bring up the profile manager and create a new profile this way or remove the profiles.ini file to force Firefox to create a new profiles.ini file and a new profile. You can check if you still have an older profile that you might be able to reuse or recover files from this profile.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
• https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update

You can find the profiles.ini file in a hidden location:

• Mac: ~/Library/Application Support/Firefox/

Hi cor-el,

Thanks for the reply.

You said that:

"You can start Firefox with the -P parameter to bring up the profile manager"

How do I "start Firefox with the -P parameter"?

You also suggested that I:

"remove the profiles.ini file to force Firefox to create a new profiles.ini file and a new profile."

I removed the profiles.ini file but that did not change anything.

I still get this message when I try to open FF:

"Profile Missing Firefox profile cannot be loaded. It may be missing or inaccessible."

Okay. I uninstalled FF by deleting the application in the utilities deleting the FF folder inside the Application Support folder. I assume this removes FF completely. I then restarted computer and downloaded a new FF application. I try to launch the new application and still get this message: "Profile Missing Firefox profile cannot be loaded. It may be missing or inaccessible." This is insane. How is this possible? Did I not wipe all vestiges of my previous FF application?

You likely left the folder with the profiles.ini file and this file is still pointing to the old, no longer existing, profile.

• ~/Library/Application Support/Firefox/
• ~/Library/Caches/Firefox/

Note Firefox uses two locations for the Firefox profile folder. One location for your personal data (e.g. bookmarks) and another location for temporary files like the disk cache, so make sure to look in locations if you cleanup manually.

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/<profile>

Hi cor-el, I'm fairly sure I removed all FF files from my hard drive before reinstalling. I reinstalled again and:

There is no Firefox folder in: ~/Library/Application Support/ ~/Library/Caches/

There is also no profile folder (nor is there a profiles.ini file) in

/Users/lewmac/Library/Application Support/Firefox/

All that exists in this folder are two subfolders:

/Users/lewmac/Library/Application Support/Firefox/Crash Reports /Users/lewmac/Library/Application Support/Firefox/Pending Pings

I wonder why FF would not create a profile folder when it is installed?