See if this helps. --> https://support.mozilla.org/en-US/questions/1477659#answer-1713872

There is a folder called; sessionstore-backups. And within this folder there are files in my case; previous.jsonlz4 recovery.baklz4 recovery.jsonlz4 sessionstore.jsonlz4 upgrade.jsonlz4-20250411030227

In the link to an identical question one is suppose to rename the file upgrade.jsonl.z4-20250411030227 to sessionstore.jzonlz4 and move it up one level in the path and place this renamed file in this location. Restart FireFox and, all my tabs which I was working on will be restored, no matter which profile it is.

I tried this, nothing was restored ?

A screenshot of the folder would be better so we can see the date and size of the files. What date did the issue happen? Firefox may have created a new profile. You can tell by going to your current profile folder and then go up 1 folder to see if there is another profile.

A screenshot of the folder would be better so we can see the date and size of the files. What date did the issue happen? Firefox may have created a new profile. You can tell by going to your current profile folder and then go up 1 folder to see if there is another profile.

The issue happened a few weeks ago, here is a screen shot of the profile with the largest size jsonlz4 files. As I mentioned here, in my previous comment. When I rename the file and move it to the current active profile then restart, the tab sessions are not restored ?

All of those files clearly have something or they would be smaller in size. So you should have closed Firefox, then remove the current sessionstore.jzonlz4 file that doesn't have your tabs. The move your renamed file into the profile folder.

Hopefully you made a backup of that folder to avoid losing old files after renaming to a name that Firefox updates during your session. You can use my Scrounger tool to back up a file as a web page of clickable links for your open (and closed) tabs: https://www.jeffersonscher.com/ffu/scrounger.html

Restart FireFox and, all my tabs which I was working on will be restored, no matter which profile it is.

No, these folders are profile-specific. If you need to copy files from one profile to another, that is an extra step.

Hopefully you made a backup of that folder to avoid losing old files after renaming to a name that Firefox updates during your session. You can use my Scrounger tool to back up a file as a web page of clickable links for your open (and closed) tabs: https://www.jeffersonscher.com/ffu/scrounger.html

Christopher said

Restart FireFox and, all my tabs which I was working on will be restored, no matter which profile it is.

No, these folders are profile-specific. If you need to copy files from one profile to another, that is an extra step.

You can only copy the session file to which the profile the session existed, correct ?

How do you copy the session file from one profile to another successfully ? Is it possible using the link you gave to have firefox open all the links at once ?

I started FireFox and opened four tabs, then I closed FireFox and to my surprise FireFox did not restore those four tabs.

Does this relate that when FireFox starts it creates its own sessionstore.jsonlz file, therefore it's difficult to override this file. Also this message is for jscher2000, I tried loading a sessionstore.jsonlz into your Scrounger but it didn't work ?

During your session, Firefox doesn't maintain the sessionstore.jsonlz4 file in real time. Instead, it maintains the recovery.jsonlz4 file in the sessionstore-backups folder. During a normal shutdown (when you go to the menu > Exit), then Firefox creates a fresh sessionstore.jsonlz4 file at the main level of the profile folder (not in the sessionstore-backups folder). So if you are replacing the sessionstore.jsonlz4 file, you need to do it after Firefox shuts down and is no longer modifying that file.

Regarding the Scrounger, I'm not sure what went wrong. Usually it can decompress the file pretty easily and show the session data in the box at the top of the page, but when it parses the file, it sometimes goes off the rails and never finishes. There is a slightly updated version on Github that may or may not work better:

https://jscher2000.github.io/Firefox-File-Utilities/scrounger.html

During your session, Firefox doesn't maintain the sessionstore.jsonlz4 file in real time. Instead, it maintains the recovery.jsonlz4 file in the sessionstore-backups folder. During a normal shutdown (when you go to the menu > Exit), then Firefox creates a fresh sessionstore.jsonlz4 file at the main level of the profile folder (not in the sessionstore-backups folder). So if you are replacing the sessionstore.jsonlz4 file, you need to do it after Firefox shuts down and is no longer modifying that file. Regarding the Scrounger, I'm not sure what went wrong. Usually it can decompress the file pretty easily and show the session data in the box at the top of the page, but when it parses the file, it sometimes goes off the rails and never finishes. There is a slightly updated version on Github that may or may not work better: https://jscher2000.github.io/Firefox-File-Utilities/scrounger.html

I tried the updated Scrounger, it works better. Although if there was a way to automatically load the Scrounged URL into FireFox, rather then load them each manually as the results when copying the sessionstore.jsonlz file isn't the same as when using your Scornger as it only loads so few URL tabs, when using the sessionstore.jsonlz file and restarting Firefox.

Hmm, I would expect all the Open Tabs in Open Windows to load automatically when you swap the session history file. Is it possible the Scrounger is showing closed windows that you can reopen from the menu? Either:

• "3-bar" menu button > History > Recently Closed Windows
• "Library" toolbar button > History > Recently Closed Windows
• (menu bar / Alt+S) History > Recently Closed Windows