Hey warlene, can you add a bit more details on which operating system and which version of Firefox you are at?

This also happened to me as well. After the Tahoe update none of non apple apps worked. Unfortunately, I had not backed up my browser to the Mozilla cloud in some time. What I am trying to figure out is if I can somehow get my bookmarks and passwords back. I did not back up to time machine till after Tahoe was installed. When I installed Tahoe, It took forever for the update to (after a couple hours I did turn my laptop off then back on). So, I figured the install did not go well so I checked all the volumes in recovery mode and there was maybe one thing first aid corrected. I backed up to time machine and then reloaded Tahoe again to see if that would help. The non-apple apps still did not work to include Firefox. I re-installed the non apple apps which work fine now Firefox works but I can't get the copy from my time machine to work alas it still did not open and said "it may be damaged or incomplete". Also for some reason Tahoe put my desktop in a folder on my new desk top. For the Version not sure, but I routinely updated Firefox, so the version should have been what ever was current about 3-4 weeks ago. Any help would be appreciated! Thank you

This also happened to me as well. After the Tahoe update none of non apple apps worked. I had not backed up my browser to the mozilla cloud in some time and I am trying to figure out if I can somehow get my bookmarks and passwords back. I did not back up to time machine till after Tahoe was installed. It took forever for the update to Tahoe (after a couple hours i did turn my laptop off then back on). So, I figured the install did not go well so I checked all the volumes in recovery mode and there was maybe one thing first aid corrected. I backed up to time machine and reloaded Tahoe again. I did have to re-install the non apple apps which work fine now firefox works but the copy from my time machine which which I created after the first but before I reloaded. Also for some reason Tahoe put my desk in a folder on my new desk top. I routinely updated Firefox, so the version should have what ever was current about 3-4 weeks ago. Any help would be appreciated! Thank you

Hey earl, just making sure I understand. Does Firefox now work for you and you lost bookmarks and history? Or it doesn't work at all?

I had to re-download and the new copy works, but I am essentially starting fresh

Got it. In that case try to see if the old data was saved in one of your profiles.

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it. The About Profiles page will open. This page should list at least one profile and could list many.

The profile that Firefox is currently using will show:
This is the profile in use and it cannot be deleted.

Please do not delete anything here; don't use any Remove buttons.

Do you have another profile named default or default-longnumber listed on this page? If so, you can check whether it is the one you were using recently by clicking its Launch profile in new browser button.

If it isn't what you want, simply close that new window.

If it IS what you want, click the Set as default profile button for that profile on the about:profiles page. Firefox will use it automatically at the next startup.

For more information see Recover user data missing after Firefox update.

Note: If your bookmarks are not available in another Firefox profile, see Recover lost or missing Bookmarks for other solutions.