have you tried searching it in history settings in your browser

I had about 250 open tabs and i cant reopen that session. Opening them one by one is about as much as i can do. Or pay 80€ for a recovery tool to find the backup that i need

One possible scenario is that Firefox was not keeping your session history file up-to-date, but 2 months is a very long time to roll back. Another possible scenario is that your main profile was inaccessible at startup so Firefox used an older one. If the browsing history is also old, then it would make sense to explore that possibility.

Otherwise:

Previewing the Contents of the upgrade.jsonlz4... File

These compressed files are a pain to view, so I created a tool on my website to list out their contents. If you want to try that, you can drag and drop it onto the large box on the following page, then click the "Scrounge URLs" button. If the one you want to use is obvious, and you don't need the currently open tabs, then you can skip this step.

https://www.jeffersonscher.com/ffu/scrounger.html

If you don't get a list within 15 seconds, that probably means the script is caught in a loop. You may need to close the tab to avoid a tab crash and then try again in a new tab.

If you get a useful list, use the "Save List" button to archive it as a web page of clickable links for future reference, in case no other approach is successful.

Manual Swap of Session Files

Here's how you fool Firefox into restoring an older .jsonlz4 file in place of the latest one:

(1) From inside Firefox, open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > Help > More Troubleshooting Information
• (menu bar) Help > More Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, find the "Profile Folder" row. On that row, click the "Open Folder" button. This should launch a File Explorer window listing the various files and folders in your profile.

(2) Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup -- a file named sessionstore.jsonlz4 should appear in the folder.

Once Firefox has stopped updating things (10-15 seconds):

(3) Right-click sessionstore-backups and click Rename, then add OLD (sessionstore-backupsOLD) and press Enter or click away to save the change.

(4) Right-click > Rename sessionstore.jsonlz4 and click Rename, then add OLD to the file name (sessionstoreOLD.jsonlz4) and press Enter or click away to save the change.

(5) Paste in the other file you want to restore, and rename it if necessary:

• Compressed file such as recovery.jsonlz4 or upgrade.jsonlz4-20221104133228 => sessionstore.jsonlz4
• Uncompressed file from a decompression tool => sessionstore.js

(6) Start Firefox and it should read the swapped in sessionstore file and restore whatever was in the substitute file; if you do not have Firefox set to restore your previous windows and tabs automatically, use History > Restore Previous Session

Any luck?

Ok I'll try and reply if it works

One issue that Ive found is that the file is 1.8 MB and the page crashes before I can even read it. The latest and more reasonable one that I can recover is one from a week ago, but it is still 1.7MB. Ill try doing it without chequing the content and hope it works

Yeah no luck, I don't know if it is because the files are corrupted or what but thanks anyway. I don't know if I can pull everything out if the history but I'll try.

One issue that Ive found is that the file is 1.8 MB and the page crashes before I can even read it.

Sorry to hear about that. If it crashes Firefox, you could try it in Microsoft Edge. Maybe it uses memory differently.

If the crash occurs before the file contents fill into the box, you can have Firefox decompress the file using a Browser Console script (the Ctrl+Shift+J console). See: https://gist.github.com/jscher2000/4403507e33df0918289619edb83f8193

That would give you the .json contents of the file which you could try scrounging, or... it's a lot of data to process in other ways.

Ill try doing it without chequing the content and hope it works

Hopefully that will work!