So what is different in comparison to the old session restore? First of all, you may notice that additional files are saved by the browser which increases the chance that one of the session restore files is not corrupt and working. And finally, upgrade.js will be tried as well.Previous.js is then used to restore the session.Recovery.js will be used if present and valid.If sessionstore.js is valid, it will be used.Here is the order in which Firefox attempts to restore the previous session on start. sessionstore-backups/upgrade.js- Session Restore data after the latest upgrade.
sessionstore-backups/previous.js - Session Restore data before the second to last shut down.sessionstore-backups/recovery.bak - Contains the state of Firefox 30 seconds before shutdown or crash.sessionstore-backups/recovery.js - Contains the state of Firefox 15 seconds before shutdown or crash.sessionstore.js - The state of the browser during the last shut down.
Note that sessionstore.js is only shown when Firefox is not open. While sessionstore.js is still stored in the main Firefox profile folder, all other files are now stored in sessionstore-backups instead. Mozilla has improved the Session Restore feature in Firefox 33. May still be useful for old versions of Firefox, and Firefox-based browsers such as Pale Moon. If it does not, press the Alt-key on your keyboard and select History > Restore Previous Session. Firefox might pick up the session automatically.Paste the copied file to the root folder.Go back to the root directory of the Firefox profile.Copy the session restore backup that you want to restore, e.g.Rename recovery.backlz4 to recovery-backup.backlz4.Rename recovery.jsonlz4 to recovery-backup.jsonlz4.Open the sessionstore-backups folder of the profile.Open the profile folder and rename the current session file sessionstore.jsonlz4 to sessionstore-backup.jsonlz4.Make sure no instance of the browser is running. Mozilla changed the format of session backup files and that means that the previous way of restoring sessions needed updating. Use these if previous.jsonlz4 fails to do the trick. upgrade.jsonlz4-"number" - previous session backups, usually created during upgrades of the browser.previous.jsonlz4 - the last session backup that Firefox created.This is the file that you want to try to restore first (unless it has a very low size).