Was using Firefox 56 with Michael Kraft's "Session Manager" extention - http://sessionmanager.mozdev.org/index.html . Unfortunately left system on, came back and found it had been unintentionally upgraded to 68, and extentions wiped out. Need to recover the tabs from a recent session. Only one 'profile' to be found. In 'sessionstore-backups' is file, upgrade.jsonlz4-(date) from time between important session and upgrade. Is there any way to decode this, or other files that would have needed data ?