Hi Yann, sorry to hear about this problem. Did you already rescue all existing session history files? Here's how:

You can open your current Firefox settings (AKA Firefox profile) folder using either

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

In the first table on the page, click the "Open Folder" (or "Show in Finder") button.

In your profile folder, double-click into the sessionstore-backups folder. Copy all files here to a safe location such as your Documents folder.

The kinds of files you may find among your sessionstore files are:

• recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.baklz4: a backup copy of recovery.jsonlz4
• previous.jsonlz4: the windows and tabs in your last Firefox session
• upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update
• some .js files from Firefox 55 or earlier

Could you take a look at what you have and the date/time of the various files to see whether you think any of them would have the missing tabs?

To preview the contents of a file, you can drag and drop it onto this page, then click Scrounge URLs: https://www.jeffersonscher.com/ffu/scrounger.html

That tool is on my site, so please let me know if it doesn't work for you.

Hi Jeff, thanks for your very quick answer ! And also very clear ! Sorry for the delay on my side...

I had played with sessionstore files before posting here, but without success. Unfortunately, the problem was I open/close firefox several times before I do a backup of theses files, so recovery "recovery.jsonlz4" and "previous.jsonlz4" are almost the same.

Thankfully, I have some bakcup file from last update. So I used the link to your website on the most recent file. This works really well, I'm pleased to retrieve almost all my tabs !! I didn't know that I got so much of them (more than 1100 ! :-\)... This is probably the origin of the crash, I need to change my mind and use the favory function to store interesting things :-)

Thanks sincerely for your help and your wonderful tool ! Thanks again for your clear answer and your time !

Best regards, Yann

Hello Yann,

Would you be so kind as to mark Jefferson's post as Chosen Solution ? ("Solved Problem" button to the right)

Thank you in advance !

(edit : typo ... )

Hello, for sure, thanks again to all and especially Jefferson for your help here !

Best regards, Yann