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Firefox (39) for Mac does not remember previous session tabs and cards with settings set to remember them

  • 20 replies
  • 1 has this problem
  • Last reply by John99

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My FF in version 39 for Mac (latest version) does not remember last session tabs and cards. It is set to remember them in preferences but it is not working.

Start with home page or blank page is working. Option to remember 'open with last session tabs and cards' behaves exactly as 'start with home page'. When I enter history menu everything is there and I can force FF to restore last session tabs but it is not what I/we want.

I was trying to restart/shut down and power back - did not help.

Downgrade to 36.0.4 did not help.

Manual update from 36.0.4 to 39 did not help.

In sync menu history is also chosen to be synced.

Any ideas please?

Thank you in advance!


All Replies (20)

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Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options)
key, and then starting Firefox. Is the problem still there?

You may have corrupt sessionstore file(s).

Type about:support in the address bar and press enter.

Under the page logo on the left side you will see Application Basics. Under this find Profile Folder. To it’s right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the sessionstore file(s). Then rename or delete it. Restart Firefox.

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Check that you do not run Firefox in permanent Private Browsing mode (Never remember history).

  • Firefox > Preferences > Privacy > Firefox will: "Use custom settings for history"
  • Deselect: [ ] "Always use Private Browsing mode"

Make sure that you do not close open windows before closing the Firefox application, but close the Firefox application (Firefox > Quit) while the window(s) are still open. Otherwise you only close the current window and Firefox won't restore that window on the next start. In case of the latter then check for "History > Recently Closed Tabs/Windows".

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I did follow your advice, thanks! Started FF in Safe Mode, got the the folder and deleted file sesionstore.js and folder named sessionstore-backups. Then restarted. Problem described above was still there plus folder sessionstore-backups is created again while file sesionstore.js is missing

When I am in safe mode and have various tabs opened and start FF in safe mode again after quiting it DOES remember tabs from previous session. While started in normal mode it DOES NOT remember tabs from previous session


My privacy settings are set to: 'FF will rememebr history'

what do you suggest to do?


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The sessionstore.js file is only present when Firefox is closed. While Firefox is running the files in the sessionstore-backups folder are being used.

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

I'm curious why this works because the System Details list doesn't show any installed extensions.

In Firefox Safe mode these changes are effective:

  • all extensions are disabled (about:addons)
  • default theme is used (no persona)
  • userChrome.css and userContent.css are ignored (chrome folder in profile folder)
  • default toolbar layout is used
  • JavaScript JIT compilers are disabled
  • hardware acceleration is disabled (Options > Advanced > General)
  • plugins are not affected
  • preferences are not affected
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Thing is that it is bare version installed with standard extensions. I did not manage to install anything additional yet.

One rectification - it is working only in safe mode. It is not working in normal mode

Are your suggestion still valid having in mind above rectification?


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mmm ... usually is an Add-on or an extension which interferes when all is otherwise working OK in safe mode.

Try reading this page here or otherwise installing this Session Manager developed for Firefox.

Modified by Dingeroo

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Just to confirm: are there any extensions showing in "Tools > Add-ons > Extensions"?

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@ Cor-el

No, the list is empty


Thanks for the article, I did check all settings and they are correct including privacy settings, browsing history, download history and so on

Honestly I'm stuck, I'm checking now with Session Manager

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You can try to disable hardware acceleration in Firefox.

  • Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"

You need to close and restart Firefox after toggling this setting.

You can check if there is an update for your graphics display driver and check for hardware acceleration related issues.

Use "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit) to close Firefox to close all open windows at once and the Firefox application.

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Interesting observation to share.

I did try toggling with hardware acceleration setting. Accidentally after closing FF by choosing 'quit' option from the dock on the FF icon I have opened FF not by clicking on its icon in the dock but by a link from mail and it opened FF itself. To my surprise it opened itself as incremental tab in FF next to all tabs from previous session! It is independent from having hardware acceleration turned on or off.

That would mean that when I start FF from a link in mail it does remember history and opens with all tabs from previous session but when I start FF by clicking on its icon (shortcut) it only opens home page.....

Any ideas why is it so?

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Maybe the shortcut needs updating?

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Additional observation

It turns out that problem exist only when I close (minimize) FF's window by clicking on the 'x' button in top left corner of the window and then turns it on back by clicking on the FF's icon in the dock.

It does not exist when I close FF by choosing 'quit' option on the icon in the dock. After such closing when opened by clicking on the icon in the dock it opens with all previous session tabs....

Strange. No idea what to do.

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@Dingeroo at al

Icon (shortcut) is installed by this instance of FF.

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It is weird, almost as though you are running two different instances of FF. Perhaps the earlier instance is still showing through those other access places where you can see all previous history, tabs, bookmrks etc. and the new instance is not showing these?

An option would be to back up earlier profile, tabs, bookmarks etc. and uninstall FF and then do a clean install of the latest version and import your profile, tabs, session history files, etc. to the new install?

Info' on how to do that is readily accessible and we can post you the links, if you decide to take that approach.

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Yes, please post the links if you can.

I will wait till tomorrow (well for me it is already tomorrow) for other opinions and if there is no other idea I would try this approach.


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What happened with the Session Manager download? If that is not working then, an easy option might be to do the following and if that does not work only then go to a clean re-install, but first an IMPORTANT NOTE:

You should not re-open Firefox when Session Restore has failed to load the previous session as you may end up overwriting the backup file with the last session of the new install. The back up file hopefully contains information that has not been modified after the previous session failed to load, which is good reason to back up and copy both files to a secure location before you do the following or anything further.

Firefox saves two files with Session Restore information to the user profile:

1. Sessionstore.js contains information about the current session.

2. Sessionstore.bak (may be 'recovery.bak' since version 33) contains session information from the previous session.

After backing up these two files to a secure place, then try deleting the sessionstore.js file which stores the current session and rename the sessionstore.bak file (which stores the previous session), to become the sessionstore.js file, then restart your PC and see how you go.

Let us know and if that doesn't work we'll move to the Plan B.



1. Sessionstore.js is stored in the main Firefox profile folder. All other files are stored in sessionstore-backups. Sessionstore.js is only shown when Firefox is not open.

2. The primary backup file is recovery.js and the secondary backup file is recovery.bak.

You can use the other session backups listed to restore sessions and to replace the sessionstore.js file in the main directory.

3. You will find previous.js and upgrade.js there as well. These files contain session information from the last shutdown or upgrade. They too can be used to replace the main sessionstore.js file.

Modified by Dingeroo

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sessionstore.bak is no longer used.

You can backup the session files in the sessionstore-backups folder in the Firefox Profile Folder to make sure not to lose possible important session data.

previous.js (cleanBackup: copy of sessionstore.js from previous session that was loaded successfully)
recovery.js (latest version of the sessionstore written during runtime)
recovery.bak (previous version of the sessionstore written during runtime)
upgrade.js-<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.js to replace the current file (make a backup copy of the current sessionstore.js).

The sessionstore.js file is created from recovery.js when you close Firefox and is removed and copied to previous.js when you start Firefox.

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cor-el that is the same instructions I gave. Why are you repeating it and why are you dogging my every post with a counter-post? It is probably only serving to confuse the client. Whose interests are you acting in?

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Thank you again for your hints and help.

I did try to work on sessionstore files - no difference.

Regarding Session Manager - honestly I did not play much with it as I'm in a position that if that functionality is supported by FF (at least should be) I do not want any additional extensions/addons to do the same. I simply do not like that kind of workaround.

Having above in mind I'm closer to clean reinstall of FF.

I'm on MAC not PC. Would you be able to provide detailed info step by step how to do a clean re-install? Of course I can deleted FF from apps list and have it installed again but I believe there are some other locations where some FF files are stored plus I must not loose my already created folders with bookmarked tabs etc.


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I will add details about a clean install. Before you follow those note a few other factors could need considering.

  • The clean reinstall should have little effect on Firefox.
    (Other than the important consideration of correcting some corruption or problem causing this issue)
  1. The clean install does not affect the Firefox Profile and the profile is where all the sessionstore related files are.
  2. First of all just try a new additional Firefox Profile. Ensure you try using that in Firefox's safe mode and with all plugins disabled by setting to never activate.
  3. Do your Firefox Profiles seem otherwise ok ?
    • The original one and the new one ?
      For instance are bookmarks saved ok ?
      Is history saved ok ? For instance visit some sites you have never visited before. Close the tabs those new tabs before closing down Firefox. Does Firefox remember them when you restart it ? (So you see the address bar autocomplete for instance)


(An easy crib. This was hidden in the magicians hat ! for anyone wanting it )

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove your Firefox program files and then reinstall Firefox . This process does not remove your Firefox profile data (such as bookmarks and passwords), since that information is stored in a different location.

To do a clean reinstall of Firefox, please follow these steps: Note: You might want to print these steps or view them in another browser.

  1. Download the latest Desktop version of Firefox from (or choose the download for your operating system and language from this page) and save the setup file to your computer.
  2. After the download finishes, close all Firefox windows (or open the Firefox menu New Fx Menu and click the close button Close 29).
  3. Delete the Firefox installation folder, which is located in one of these locations, by default:
    • Windows:
      • C:\Program Files\Mozilla Firefox
      • C:\Program Files (x86)\Mozilla Firefox
    • Mac: Delete Firefox from the Applications folder.
    • Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.
  4. Now, go ahead and reinstall Firefox:
    1. Double-click the downloaded installation file and go through the steps of the installation wizard.
    2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.