Yes, and no. Your old profile is moved to a folder on your desktop. Then some data is copied to a new profile. Sometimes the data does not get copied, but only sometimes.

If there is something you want from the old profile, it will be waiting for you on the desktop.

Refreshing Firefox {web link} is a LAST RESORT ! !

Refreshing Firefox -- easily fix most problems

If you're having problems with Firefox, refreshing it can help. The refresh feature fixes many issues by restoring Firefox to its factory default state while saving your essential information like bookmarks and open tabs. Everything else, like user settings and add-ons, are removed. Note: Refresh saves your old profile to the desktop in a folder called Old Firefox.

I lost tons of stuff and bringing it over from the Old Firefox Data folder is not clear at all. This is a disaster. All my settings were changed when I did this. It would be nice if they told us but Mozilla couldn't be bothered including that little tidbit in their Refresh Firefox option or I didn't see it.

I've had huge problems with my settings being reset for no reason as well. I'll start up and everything is gone. Extensions were even removed a couple of times. Then later settings were reset and extensions were there.

Firefox is really acting strangely. It pays to know how to back up all your settings/preferences/extensions/etc so you can reset it yourself when Mozilla decides to do its little upheaval mode on you.

Its a great browser but its getting much worse because they seem to be taking control away from the user. Or maybe its just the things I use. Still, nothing else comes close. Compared to Chromium based browsers (though Opera does its best with Alphabet's restrictions), Firefox is miraculous. Chrome based browsers gives you almost zero control.

Backup, backup, backup.

Hi moz2u, if you want help restoring files, please start a new thread, this one is already marked as solved.

Also, as you probably know, Firefox 67 made big changes to Firefox profiles, so we may have different suggestions for you now than back in the day.