If I recall correct the last Browser windows is what the browser saves to restore last session any other browser will not have those saved. What you want to do is bookmark the site so that they will not be lost when closing the Browser.

Apple says it's debatable if the windows will be restored or not, given how Firefox and the new os may interplay.

So to protect myself I just want a) or b) as above. Are you saying I could do a) or b), and exactly how please?

Firefox stores session data in sessionstore.jsonlz4 in the Firefox profile folder. This file is only present when Firefox is closed.

You can backup certain files in the current profile folder with Firefox closed to have a backup of your personal data.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

Note that best is to avoid restoring a full profile folder and only restore important files that are safe to restore/transfer.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins) and key4.db (encryption key/primary password) for logins saved in the Password Manager
• cert9.db for certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

Hi cor-el, I'm unclear what your definition of a "session" is in this context, also which "personal data" and which files you're referring to.

If I have understood your answer correctly, you're saying I have to shut Firefox to see a file which lists all my open tabs across all windows? How does it sort those tabs across my organised windows in that file and what view would I get? A simple example would be great.

Thanks.

You start the session when you start Firefox and end the session when you quit/exit Firefox. During the current session, session data is stored in the sessionstore-backups folder.

You will normally find these files in the sessionstore-backups folder:

• previous.jsonlz4 (cleanBackup: copy of sessionstore.jsonlz4 from previous session that was loaded successfully)
• recovery.jsonlz4 (latest version of sessionstore.jsonlz4 written during runtime)
• recovery.baklz4 (previous version of sessionstore.jsonlz4 written during runtime)
• upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file with Firefox closed and restore this session when you start Firefox.

• make sure to backup the current sessionstore.jsonlz4

The files have the .jsonlz4 file extension and that means that they are compressed, so you can't inspect them easily. A sessionstore file contain s a list of all open tabs and tabs that appear under "recently closed tabs", a separate list for each window, and also includes the cookies for each tab.

You can look at this tool to inspect a compressed jsonlz4 sessionstore file. This tool works locally, no uploading done.

• https://www.jeffersonscher.com/res/scrounger.html

OK, thanks. It's a much more fiddly way of seeing them than I hoped - I wanted it to be clearly visible from the main Firefox interface, but it's a way! Thanks.

l569, I wonder if an add-on such as Tab Stash would be of interest?

It essentially saves opened tabs as bookmarks, which can be organised into groups.

And since these are just Firefox bookmarks, you can view them in the UI, and re-open batches of them in one go.

Then you would just need to import your bookmarks into any new Firefox, and then you'd have the ability to recreate your windows using them.

Note, I have not personally used this add-on, but the description sounds similar to what you want so thought I'd mention it as a possible solution.