Has anyone looked at this entry? Does anyone care?

Let's start with Session Manager or Tab Mix Plus. Any sessions you saved using these extensions should have been preserved in your Firefox profile folder, but would have been inaccessible. When you said you were able to import it, was that using Tab Session Manager? Its reviews are very mixed as it is still developing, so that may not be a good workaround for a while.

To locate an old version of Firefox, please use this article: Install an older version of Firefox. It works best if you visit using Firefox; then it can provide a specific previous version link. Otherwise, it has a very general link.

For future reference, Firefox releases with "b" in the version are pre-release beta test versions.

If you feel that you won't be ready to use Firefox 57 for an extended period of time, you could consider using the Extended Support Release of Firefox 52. That's Firefox 52 with another 10 months of security updates, and will be maintained through next Spring.

More information on ESR: https://www.mozilla.org/en-US/firefox/organizations/faq/

Now... what about your old data that was removed, either by manual deletion or by some kind of uninstaller? You'll want it back, I assume.

If you can't recover it from the Windows Recycle Bin, you could investigate recovering a snapshot of your data from a Windows Restore Point. I never recommend using System Restore, but you can "mine" your restore points for relevant files. Here are some links you'll need:

• Set Windows to show hidden files and folders: https://support.microsoft.com/en-us/help/14201/windows-show-hidden-files
• Install http://nicbedford.co.uk/software/systemrestoreexplorer/

In the most recent restore point, drill down through the profile path:

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

and see what folders are available there. You can copy a folder out to a neutral location (e.g., Documents folder) so you can selectively restore data from it. I won't extend this post with all those details, but this article covers the built-in kinds of data:

Recovering important data from an old profile

Thank you for your reply. I will consider moving to the new version of Firefox when a session manager is working at the same level at the legacy Session Manager (NOTE: it is critical that there is an option to always open the session manager BEFORE it starts windows to be able to disable a problem window/tab for it to be usable). In the mean time, I will move to 52.0.2esr (using the technique below).

Is there any way to be informed when a new session manager is fully functional?

I later found backups of the old sessions in an "Old Firefox Data" folder on my Desktop (and have copied it elsewhere, also), so have been able to recover the previous session.

Today I installed 56.0b9 and opened it with shift/click to get into Safe Mode (again, discovered since my first post), disabled update and then reopened it and the old session manager appeared.

If you go with ESR, the current release is on this page: https://www.mozilla.org/firefox/organizations/all/

PopInID said

Is there any way to be informed when a new session manager is fully functional?

Hmm, I don't think so because it may be called something different.

Another new session management add-on:

https://addons.mozilla.org/firefox/addon/my-sessions/

In the process of moving to Firefox 52.0.2esr x64 (I have tried both 32-bit and 64-bit versions) something is missing and I can no longer see or save bookmarks. Clicking "Bookmarks->Show All Bookmarks" opens a blank Library window. Clicking "import and Backup->Restore" shows a list of 14 items. Clicking on one pops up a window with "This will replace all of your current bookmarks with the backup. Are you sure?". When I click on "OK" a new window pops up with "Unable to process the backup file." I have another desktop system and after installing Firefox 52.0.2esr x64 the bookmarks are working. I have tried closing other programs, uninstalling, rebooting and reinstalling and still no bookmarks.

What am I missing?

Hi PopInID, have you seen any error message like the one covered in the following article:

Fix "The bookmarks and history system will not be functional" error message

If that is not the issue, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

No, starting in safe mode does not fix the problems. Note that, not surprisingly, both bookmarks and the Bookmarks Toolbar are not working.

Your places.sqlite database -- the file which stores your history and bookmarks together -- might be corrupted or locked. This may be a result of using a profile that ran Firefox 55 or later in Firefox 52. However, I am not aware of all the details. The method described in the previous article removes the Places database and starts fresh. If you try that, please keep a backup of the file.

Success! I renamed the places.sqlite file and copied one from another, previous profile and bookmarks are working. Thank you.

jscher2000 said

Your places.sqlite database -- the file which stores your history and bookmarks together -- might be corrupted or locked. This may be a result of using a profile that ran Firefox 55 or later in Firefox 52. However, I am not aware of all the details. The method described in the previous article removes the Places database and starts fresh. If you try that, please keep a backup of the file.

I had this experience too. I run Firefox on two computers. The older one, on Windows XP, won't run any Firefox newer than 52. The newer one, on Windows 10, auto-upgraded to Firefox 57. Until today, I shared my bookmarks by sharing file places.sqlite between them, But today, suddenly, as far as my older machine was concerned, all the bookmarks vanished! It seems that sharing file places.sqlite may no longer be a safe way to share bookmarks between the two machines. Instead, I am exploring Firefox Sync for this purpose: https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer

PopInID said

Success! I renamed the places.sqlite file and copied one from another, previous profile and bookmarks are working. Thank you.

Of course that reverted all your bookmarks to their state as of the date of that previous profile.

Hi Rich Pasco, if you have a newer bookmark file you want to restore in place of the current (older) set in places.sqlite, you can do it. See:

Restore bookmarks from backup or move them to another computer