The Mozilla Answer page: https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile#w_copying-files-between-profile-folders, provides some pretty good information about which files to recover, but, doesn't include the general population's need to recover their last sessions, so a mention on this same page would be extremely helpful. Next, I found the places.sqlite file will update automatically without shutting down Firefox (most likely when the computer is put to sleep and then awakened). A warning about this little known file updating would be helpful to those who learned about their lost history, but choose to wait until later, like recovering it prior to shutting down, but they will have lost the opportunity when the places.sqlite file self updates itself automatically (who knows exactly when or why) I'd like to see this important information placed your answer on this same (above) troubleshooting page, because when I loose history caused by a proper shut down, I'll need to your page infor to remind me what to be cautious about. And I don't believe you have created a back up file to places.sqlite to which I can recover and rename yet, because I believe the closest name to it has very little memory in it, but I could be wrong.