Here is a screen shot of the error message

Did Firefox crash before this occurred?

As the first step, I suggest creating a new profile. It won't have your settings in it, but will allow you to get up and running and then we can suggest where to look for your bookmarks and other missing data.

This article has the steps to create a new profile: Profile Manager - Create, remove or switch Firefox profiles.

Note: if the article doesn't show steps for Mac, use the "Editing Tools" bar on the left to switch the page to Mac.

The genesis of the problem was a failed attempt to load a profile from a version of Firefox on a different computer. As mentioned before, I have a profile in place but it does not seem to be able to use/see it. Also, as I understand it, using the profile manager requires Firefox to be open, which is impossible since Firefox will not open.

You do not need to be able to open Firefox to use the Profile Manager, at least not on Windows. But if you don't want to try it, you could try a different approach.

Thanks for the screen shot. Is that folder in the Profiles folder the one you copied over from another computer? And at some point you deleted the one that Firefox had created there when it installed? That would cause this problem because Firefox is still looking for the old folder, and is not aware of the new one.

To remedy that:

• Make a backup copy of the profiles.ini file (you see it in the Firefox folder) for possible future use

• Open the profiles.ini from the Firefox folder in a text editor

• Edit the path listed in profiles.ini to match the actual name of the profile folder you copied into the Profiles folder. For example, if it says:

Path=Profiles/abcd1234.default

edit that to

Path=Profiles/4d3wwrf0.default-1392077192831

Then save the modified file.

When you start Firefox, can it now find your profile folder?

That solution worked fantastically. You, sir, win the internet for today! Thank you so much. For others who may have this issue. I will answer your questions specifically.

Q:Is that folder in the Profiles folder the one you copied over from another computer? A: Yes it is.

Q:And at some point you deleted the one that Firefox had created there when it installed? A: Yes. In hindsight, that was ill advised.

You get this error when to profile that is marked as Default=1 in profiles.ini is no longer present.

Note that you can use the Profile Manager to create a new profile and use Choose Folder to register a profile you copied.

See also:

• https://support.mozilla.org/kb/how-run-firefox-when-profile-missing-inaccessible
• http://kb.mozillazine.org/Recovering_a_missing_profile