This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Session lost after update

more options

session is completely gone. I tried to restore it via various help articles and forum posts but without success.

I see a stg-backups-ff-126.0.1 fodler in my download folder which contains information about tabs that I had open. But I don't know how to use firefox to use that file.

I alos tried to the \sessionstore-backups folder with files named like "previous.jsonlz4" but I do not get the menu option for restoring a session.


from a file named "error-sessionrestore-1718212432477.txt": 1718212432149 SessionStore ERROR The session file is invalid: : TypeError: state.windows[0] is undefined(resource:///modules/sessionstore/SessionStore.sys.mjs:1163:11) JS Stack trace: initSession@SessionStore.sys.mjs:1163:11 onBeforeBrowserWindowShown/<@SessionStore.sys.mjs:2035:35

session is completely gone. I tried to restore it via various help articles and forum posts but without success. I see a stg-backups-ff-126.0.1 fodler in my download folder which contains information about tabs that I had open. But I don't know how to use firefox to use that file. I alos tried to the \sessionstore-backups folder with files named like "previous.jsonlz4" but I do not get the menu option for restoring a session. from a file named "error-sessionrestore-1718212432477.txt": 1718212432149 SessionStore ERROR The session file is invalid: : TypeError: state.windows[0] is undefined(resource:///modules/sessionstore/SessionStore.sys.mjs:1163:11) JS Stack trace: initSession@SessionStore.sys.mjs:1163:11 onBeforeBrowserWindowShown/<@SessionStore.sys.mjs:2035:35

All Replies (2)

more options

Sorry to hear about this problem. There is an issue with Firefox 127 on the first run where if you cancel the Primary Password prompt that appears right after startup, Firefox launches in a broken state and doesn't restore your session. It happened to me, and here's what I did:

Assuming previous.jsonlz4 still dates back to before the problem:

(1) right-click the file, Ctrl+C to copy, then Ctrl+V to paste

Windows creates "previous - Copy.jsonlz4"

(2) Exit out of Firefox normally.

(3) right-click recovery.jsonlz4 and rename to recoveryOLD.jsonlz4

(4) right-click "previous - Copy.jsonlz4" and rename to recovery.jsonlz4

(5) In the Windows Files Explorer address bar, click up a level to the profile folder

(6) If you find sessionstore.jsonlz4, right-click rename it to sessionstoreOLD.jsonlz4 (this makes Firefox more inclined to grab that recovery.jsonlz4 file at the next startup)

Finally, start up Firefox again.

Success?

Helpful?

more options

By the way, I think "stg" may refer to the Simple Tab Groups add-on? I don't know how to use that data, but the author might have a help/wiki page on that.

Helpful?

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.