Get a thumb drive and plug it in the old computer. Open the profiles folder in your user folder; C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles

Copy the profile you want onto the thumb.

Now plug the thumb into the new computer. Follow the above instructions but copy from the thumb.

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

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

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

" I've copied the entire Mozilla folder from AppData and overwritten the Mozilla folder on my Mac with it, ..."

Does the Profile name in the profiles.ini file match the Profile folder name? If not, that's your problem.

If Firefox can't find the Profile it is looking for, it will just create a new Profile. The profiles.ini file needs to be copied over, too - or you need to edit the Profile name which is in the profilles.ini file for Default=1.

You shouldn't copy a full profile across platforms as there are likely files in the profile that contain absolute file paths. The prefs.js file is a likely candidate for containing OS specific data.

Try to keep it safe and only copy personal data that you really need and reinstall the extensions or only copy their folder and not their settings stored in the prefs.js file to allow them to initialize properly.

See:

• https://support.mozilla.org/kb/Recovering+important+data+from+an+old+profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

For the Bookmarks you can copy the places.sqlite file (history and bookmarks) and the bookmarkbackups folder. For the passwords you need logins.json and key3.db. You can recover other SQLite database files and files like sessionstore.js for the (pinned) tabs and tab groups.

the-edmeister said

" I've copied the entire Mozilla folder from AppData and overwritten the Mozilla folder on my Mac with it, ..." Does the Profile name in the profiles.ini file match the Profile folder name? If not, that's your problem.

I copied the profiles.ini folder, but I don't know how to open it to view the contents on a Mac, to verify the file path.

I'll check out the other options posted here and check back in tomorrow.

profiles.ini should be compatible, but the folder structure on Mac is possibly different on Mac.

• ~/Library/Application Support/Firefox/Profiles/<profile>/
• C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile>\
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Also make sure to check the file and folder permissions (read/write access).

You should find the profiles.ini file in this hidden location:

• Windows: %AppData%\Mozilla\Firefox\
  *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\
• Mac: ~/Library/Application Support/Firefox/
• Linux: ~/.mozilla/firefox/

It is still best to let Firefox create a new default profile (delete profiles.ini to force a new default profile) and only copy the minimum of files.

Thank you! Mac does, indeed, store this information somewhere else (which is very strange, because I didn't create that Mozilla folder; it did that itself -- but then put the Firefox data somewhere else).

I moved all the other files and folder into the proper folder and then renamed my transferred profile to the new default and as far as I can tell so far, everything is working great.

Much appreciated!