I assume you don't see these, but if you do, click one of them:

• "3-bar" menu button > History > Restore Previous Session
• (menu bar) History > Restore Previous Session

Firefox creates numerous session history files, but because session history is only for the immediately previous session, it is unfortunately too easy to lose it. Could you start by making a backup of your existing session history files? Here's how:

(1) To open your profile folder...

You can 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 and click the "Open Folder" button on that row. This should launch Windows' File Explorer listing the contents of your current profile folder.

(2) Copy out session history files

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

(3) What files did you find?

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

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 a tool on my site, then click Scrounge URLs:

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.

Some reasons that Firefox might not restore your previous session include:

• "browsing history" was cleared at the last shutdown or manually -- this includes session history files that track your open tabs; make sure you have Firefox set to "Remember history" in Settings/Privacy & Security/History
• profile change -- either you are using a completely new profile (but you wouldn't have any of your data, so that's unlikely), or a Refresh ("tune-up") went awry
• external cleaning software zapped your data

firefox was set to open previously opened tabs. There is no restore session showing up. I am so frustrated!! To even follow all those steps to even get to the session store folder is cumbersome. I'll try to find it but...

I assume you don't see these, but if you do, click one of them:

• "3-bar" menu button > History > Restore Previous Session
• (menu bar) History > Restore Previous Session

---

Firefox creates numerous session history files, but because session history is only for the immediately previous session, it is unfortunately too easy to lose it. Could you start by making a backup of your existing session history files? Here's how:

(1) To open your profile folder...

You can 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 and click the "Open Folder" button on that row. This should launch Windows' File Explorer listing the contents of your current profile folder.

(2) Copy out session history files

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

(3) What files did you find?

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

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 a tool on my site, then click Scrounge URLs:

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.

Why should I use your website to drop my files?? This doesn't make sense to me. I don't know who you are or why Firefox isnt helping me.

I got to sessionstore but don't know how to save or open these files. None look like they would have the tabs I am wanting to restore. 3 are from the last 30 min and other 3 are older.

You can use my page to see what is in the files, otherwise, you can't see what's in them. Seeing the file contents is optional, because you can look at the dates/times and file sizes to get a sense of whether any of the files in the sessionstore-backups folder are likely to have your missing tabs. So is there anything promising there?

I got to sessionstore but don't know how to save or open these files. None look like they would have the tabs I am wanting to restore. 3 are from the last 30 min and other 3 are older.

How old is the latest one with a name similar to upgrade.jsonlz4-20210622155641 (I bolded the date that Firefox 89.0.2 was built, which would be the very most recent upgrade snapshot).

I did use your site to see what was there. But I guess I still have to go through and have to log in again to all the pages that I had left open that I actively use? This is the rub, where FF not saving my tabs as set up is costing me so much time. I have to look up passwords etc. So time consuming. thanks for your detailed response. I guess there is no easy way to simply restore what was there unless I missed something??

I did use your site to see what was there. But I guess I still have to go through and have to log in again to all the pages that I had left open that I actively use? This is the rub, where FF not saving my tabs as set up is costing me so much time. I have to look up passwords etc. So time consuming. thanks for your detailed response. I guess there is no easy way to simply restore what was there unless I missed something??

So let's say one of your files is the one you want to restore. You can trick Firefox into restoring it through some convoluted steps.

Session Restore - Manual Swap

There are several steps:

(1) From inside Firefox (the profile where you want to restore an older session), 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 Windows 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. (If it never appears, don't be alarmed.)

(3) Once Firefox has stopped updating things, while viewing the main level of the profile folder, rename one folder and two files:

(i) right-click the sessionstore-backups folder > Rename to sessionstore-backupsOLD

(ii) right-click the sessionCheckpoints.json file > Rename to sessionCheckpointsOLD.json (if you see a sessionCheckpoints.json.tmp file, right-click > Delete it)

(iii) right-click the sessionstore.jsonlz4 file > Rename to sessionstoreOLD.jsonlz4 (if you see a sessionstore.js or sessionstore.bak file, right-click > Delete it)

(4) Copy in the file you want to restore, and rename it with the name appropriate for its format:

• Compressed file such as previous.jsonlz4 => sessionstore.jsonlz4
• Uncompressed file such as previous.js => sessionstore.js

If you are viewing the list in alphabetical order, the name should appear close to the sessionCheckpointsOLD.json file. (If not, maybe there's a typo?)

(5) 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

If Firefox says it's having trouble and gives you a choice, restore your session.

Any luck?