The important data is under the hidden path:

[device:]\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles

Do you have access to that path on the old drive (or the clone made from it)?

You may need to enable viewing of hidden files and folders: https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5

You either can copy/paste selected files to your new Firefox installation, or try a wholesale "transplant":

• Recover important data from an old profile
• https://support.mozilla.org/en-US/questions/1474421#answer-1687884 (the source folder will be your recovered data from your other computer)

OK, I was able to access the hidden files in the PROFILES folder...attached. However, given the random(?) alphanumeric file designations, I have no clue as to which might (hopefully) be the desired profile?! I can report the file size of profile folders...

7WQ 41.9MB 550 576MB AFT 0MB MHF 7.39MB RUV 0MB V7Y 48.3MB Y0SS 0MB

Should I copy the full PROFILE folder to my new harddrive...or just some piece thereof? Thanks.

You can check each profile folder's bookmarkbackups folder to get a sense of when that profile was last updated. The creation date is part of each file name in that folder.

I don't know whether it's worth having all those folders on your hard drive. Probably only one of them is going to be valuable to you.

By the way, the folder names ending with a numeric string were created by the Firefox Refresh feature (sometimes called a Tune-up). You can convert those numbers to dates to determine when those profiles were created using a site like: https://www.epochconverter.com/

The folder names ending with .DEF are 8.3 names. This implies an incomplete recovery if the full file name attribute couldn't be reconstructed. Fingers crossed if you need to use one of those.

Thanks. I copied the recovered PROFILES folder from the USB to the FIREFOX subfolder on the new SSD...after copying the "orig" one elsewhere, uninstalling and then reinstalling FIREFOX. Should superfluous files be deleted from the PROFILES folder being installed? However, during install, popup message indicates that PROFILE cannot be found?! Why is install not finding the "new" folder? Googling suggests using PROFILE MANAGER...but hard to do with Firefox not running? Also saw something about deleting an "ini" file assuming I could find it.

Okay, hold on. That wasn't the procedure I described. As long as you are resurrecting the ENTIRE old setup, transfer over these two files from the Firefox folder where you found Profiles:

• installs.ini
• profiles.ini