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Firefox 67 won't restore previous sessions

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Hi, Firefox 67 recently automatically downloaded onto my Mac computer that uses High Sierra. Since it downloaded, when I quit Firefox and then reopen it, it no longer restores my previous sessions even though it is checked in my preferences to do so. I have to start all over when I open Firefox and this is the first time this happened since I have been using it for over 15 years. What can I do please? Thanks.

Hi, Firefox 67 recently automatically downloaded onto my Mac computer that uses High Sierra. Since it downloaded, when I quit Firefox and then reopen it, it no longer restores my previous sessions even though it is checked in my preferences to do so. I have to start all over when I open Firefox and this is the first time this happened since I have been using it for over 15 years. What can I do please? Thanks.

Alle Antworten (20)

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You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Type about:support<enter> in the address bar.

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

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Locate the above file. Then rename or delete it. Restart Firefox.

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Hi, unfortunately I don't understand your answer. Are you talking about within Firefox I will find these folders?

And "Type about:support" in what address bar? My finder address bar?

And "Delete all sessionstore* files and the sessionstore-backups folder." Where are these files? I have never had to do anything with Firefox before. I don't have a clue how to do any of this, could you explain please?

Thank you! Martha

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Make sure you do not run Firefox in permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History).

  • Options/Preferences -> Privacy & Security
    Firefox will: "Use custom settings for history"
  • remove checkmark: [ ] "Always use Private Browsing mode"

Do you see files in the sessionstore-backups folder in the profile 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 (make sure to backup the current sessionstore.jsonlz4).

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Thanks. I found the profile folder and session backups.

When you say: "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 (make sure to backup the current sessionstore.jsonlz4)", should I then pull out the present backup folder and delete it or leave both the old one and the new one?

And how do I back it up? Do you mean do a whole computer backup onto an external drive?

Thanks much! Martha

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I need more help. I did what was suggested and copied the sessionbackup folder and put it in my profile, renaming it "sessionstore.jsonlz4" I did this with firefox closed, then I reopened it and it is still not remembering my tabs. In general preferences, "Restore previous session" on startup is checked, and when I go to history and click "Restore previous windows" it doesn't work either. What do I do now? Thanks, Martha

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mpoinar said

. . . should I then pull out the present backup folder and delete it or leave both the old one and the new one?

Never remove a backup unless you know it is no longer needed. On that subject,

Back up and restore information in Firefox profiles.{web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.

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mpoinar said

. . . . it doesn't work either. What do I do now?

Does this help?

Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

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Nothing is working. I did remove the old session back up folders and put them on my desktop.

Wouldn't it be easier to delete firefox 67 and all the places I can find on my computer and install a new one? Or would removing the preference folder work?

Thanks for your patience. Martha

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The other thing is I can't get into the history anymore where it says to "restore previous sessions" not that it was working anyway.

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Hi Martha, you have two helpers here already, but I wanted to reply to one of your follow-ups:

mpoinar said

I need more help. I did what was suggested and copied the sessionbackup folder and put it in my profile, renaming it "sessionstore.jsonlz4" I did this with firefox closed, then I reopened it and it is still not remembering my tabs. In general preferences, "Restore previous session" on startup is checked, and when I go to history and click "Restore previous windows" it doesn't work either. What do I do now? Thanks, Martha

What you can do to induce Firefox to use an old session history file such as recovery.jsonlz4 at the next startup is to place a copy of that file (not the entire sessionstore-backups folder) in your profile folder while Firefox is closed, remove the unwanted newer sessionstore.jsonlz4 file that doesn't have the tabs you want, and rename recovery.jsonlz4 to sessionstore.jsonlz4. Then at your next startup, Firefox either should restore that automatically, or you can use

"3-bar" menu button > Restore Previous Session


Meanwhile, it seems you might ALSO have a problem with one of these if Firefox can't find your previous session at startup:

  • Session history is not being written to the recovery.jsonlz4 file as you browse, OR
  • Session history is being cleared at shutdown (for example, due to a History setting), OR
  • Session history is being cleared between sessions by a "cleaning" program

I'm going to step back but hopefully the other volunteers can help you check on those potential issues, too.


Finally, as an emergency workaround, you could install one of the session management extensions. They store your data either in extension data storage (a database) or in bookmarks. This provides an alternate way to restore your tabs when Firefox's feature fails. I haven't tested them recently, but these are the ones I hear about most often -- please check whether they record new tabs automatically as you go, or whether you need to trigger them to save your tabs:

Use database storage:

Use bookmark storage:

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One more thing please? I checked on Firefox to comment when I quit. It is saying that tabs in non-private windows will be restored. Are my tabs private windows and if so, how can I change them to non-private windows?

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mpoinar said

One more thing please? I checked on Firefox to comment when I quit. It is saying that tabs in non-private windows will be restored. Are my tabs private windows and if so, how can I change them to non-private windows?

I think the tabs mentioned in that box are only the ones in regular (non-private) windows. Normally you can recognize a private window by a white-on-purple mask icon toward the right end and a purple new tab page.

If you are using automatic private browsing, those special features are not displayed, but I think Firefox will close without even mentioning session restoration. This was one of the things cor-el had you check here:

cor-el said

Make sure you do not run Firefox in permanent Private Browsing mode (Always use Private Browsing mode; Never Remember History).
  • Options/Preferences -> Privacy & Security
    Firefox will: "Use custom settings for history"
  • remove checkmark: [ ] "Always use Private Browsing mode"
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jscher2000, thanks for your help but I think it's more complicated than that because I just tried Firefox on my other computer where it was working fine earlier today and DARN! It downloaded the 67 update and now that one now won't remember my tabs either! I didn't know how to stop the update and was yelling "NO NO NO" the entire time. This has to do with Firebox 67 on Macs! The one I've been talking about this entire time is on my MacBook Pro but the Mac I just checked is on my iMac! Two different computers. Firefox needs to fix this!

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Hi Martha, are your two Firefoxes connected by Sync?

Could you double-check that Firefox is not set to clear history at shutdown:

  • Mac: "3-bar" menu button (or Firefox menu) > Preferences
  • Windows: "3-bar" menu button (or Tools menu) > Options
  • Linux: "3-bar" menu button (or Edit menu) > Preferences
  • Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

In the left column, click Privacy & Security

Then on the right side, scroll down to the History section and select

Firefox will: Use custom settings for history

Make sure you do NOT have a checkmark for "Clear history when Firefox closes".

If you want to use that feature with some types of data, use the Settings button to the right of it to confirm that Browsing & Download History are not being cleared.


In case this is a systemic problem for Firefox on Mac -- I was away for a week and am just starting to catch up today -- you may want to try one of the add-ons I mentioned earlier as a workaround.

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jscher2000 and the others who have helped me, Firefox 67 seems to do this with the newer Mac software. I have High Sierra (10.13.6) on the laptop and Mojave (10.14.2) on the new iMac and those are the ones that the tabs no longer work on. My much older computer that has an older Mac software on it (10.10.5) just also updated Firefox to 67 and that one so far is working ok.I am holding my breathe and hoping the one doesn't become corrupted either. So Firefox needs to fix whatever the problem is with the newest Mac softwares. Sigh. In the meantime I have to leave firefox open on my new iMac and on my MacBook Pro.

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Hi Martha, can you tell whether Firefox is updating the session history file as you browse? In particular, Firefox should update the recovery.jsonlz4 file as often as every 15 seconds as you open/close tabs or change pages in tabs. To check on that:

Open your profile folder from the Troubleshooting Information page. Either:

  • "3-bar" menu button > "?" Help > Troubleshooting Information
  • (menu bar) Help > Troubleshooting Information
  • type or paste about:support in the address bar and press Return

In the first table on the page, click the "Show in Finder" button. If Firefox selects a semi-randomly-named folder (like b29zw4x0.default), double-click into it.

In your profile folder, double-click into the sessionstore-backups folder. Depending on the way your Finder is set up, the last modified date-time might be listed, or you might need to do something to view it.

Is Firefox keeping recovery.jsonlz4 up to date?

Note: The recovery.baklz4 usually is the immediately previous version of the file, so it's normal to lag a minute or two behind.

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Aren't there any sessionstore files created 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 (make sure to backup the current sessionstore.jsonlz4).

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

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Jscher2000, I am not logged into sync and never have been. We don't even use wifi, we use direct ethernet connections.

My history is set to remember all history on all 3 computers. Clear history is not checked.

On the last question you had, I checked "recovery.jsonlz4" on the two computers having problems and the times and dates were correct.

I am impressed with all your knowledge about this and appreciate your help.

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Cor-el, Yes they are there. But I'm not sure if I should continue on this path because my second computer downloaded 67 a few minutes ago and that also is not remembering tabs now. I have never logged into auto-sync so it's more than just my one computer now.

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It sounds that Firefox isn't created a sessionstore.jsonlz4 file in the main root profile folder.

You can check for sandbox security issues.

You can set this pref to 2 or 1 on the about:config page to reduce the sandbox security level.

  • security.sandbox.content.level = 1
  • close and restart Firefox to make the change effective.

If '1' still doesn't have effect then try '0' to disable the sandbox.

If this didn't work then undo/reverse the change and reset the pref via the right-click context menu to the default value.

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

See also:

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