Rather than write out 5 paragraphs, let me ask: Which data do you want to recover?

And for possible future reference: Recover important data from an old profile

Recently closed windows and bookmarks are most important.

Bookmarks

You can roll back bookmarks to the last backup pretty easily. Here's how:

(1) Find the file you want to restore

In Old Firefox Data, drill down into the profile folder (name varies, but often ends with default-release) and into the bookmarkbackups folder. The files have their creation dates in their names, so it shouldn't be too difficult to identify the latest one. They also have the number of items in the name, so you should see that number gradually get larger if you save new bookmarks frequently.

For convenience, I suggest you right-click > Copy on the file you want to restore and then right-click > Paste the file on your Windows desktop.

(2) Restore the file

This will replace your newer set of bookmarks with the contents of the backup file. See the steps in the following article (you'll need to select "Choose File" from the menu and point Firefox toward the file you dropped on the desktop):

Restore bookmarks from backup or move them to another computer

Success?

Open Windows and Tabs

Unfortunately, Firefox doesn't have a convenient method to merge an old session history file with the current session. You can roll back to the earlier session by switching some files so Firefox uses the older one when it starts up.

First, if you haven't already tried using the History menu, check for:

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

If they are missing or grayed, check either:

• "3-bar" menu button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

If you've opened/close Firefox a few times, those probably aren't useful.

Next, to find the session history from the moment of Refresh, check for these files (in order from latest to oldest):

• [Desktop]\Old Firefox Data\[profile.folder]\sessionstore.jsonlz4 - when Firefox shuts down normally, this is the file that it uses to restore your previous session windows and tabs
• [Desktop]\Old Firefox Data\[profile.folder]\sessionstore-backups\recovery.jsonlz4 - when Firefox is running or crashed, this is the file that it uses to restore your previous session windows and tabs
• [Desktop]\Old Firefox Data\[profile.folder]\sessionstore-backups\recovery.baklz4 - backup for recovery.jsonlz4, usually less than a minute behind
• [Desktop]\Old Firefox Data\[profile.folder]\sessionstore-backups\previous.jsonlz4 - previous session as of the time of Refresh
• [Desktop]\Old Firefox Data\[profile.folder]\sessionstore-backups\upgrade.jsonlz4-<build_id> - one or more snapshots created during automatic updates

Preview Option

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?

What kind of problems (if any) did you have to make you use the Firefox refresh feature ?