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Recently Closed Windows and Tabs have been erased by "Forget"

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Last night I decided to check the monthly weather forecast just before going to bed. I googled, "weather" then clicked through to a website before realizing it wasn't the one I meant to click. I backed out and clicked another link further down the list. I thought to myself, "That's going to screw me up in future because the wrong website will be a visited link and I'll mistake it for my preferred site."

I'm a long-time Firefox user and upgraded to Quantum when it first came out. I had made a cursory inspection of some of the new features at that time, and remembered the little counter-clockwise arrow in the toolbar was supposed to be a shortcut for deleting a set time frame of browsing history. Remembering this, I clicked it and a little menu popped up with options for how much history to forget. I clicked the option to forget 5 minutes.

I'd had multiple windows with multiple tabs open and they all disappeared instantly. I don't know if the browser crashed or simply intended to restart itself, but when it reopened there was only one window with no tabs.

I quickly hit the three bar menu button in the top-right and navigated to Library > History > Recently Closed Windows. Both this menu and Recently Closed Tabs were entirely empty.

My secondary Windows were of secondary importance, but my first and primary window had a large number of pinned and ordinary tabs that I did not want to lose. Tabs that I have been saving for months - some more than a year. Many that I migrated from Firefox I to Quantum. In the past, they have always been recoverable through the History. Now they seem to have been erased without a trace because I clicked, "Forget 5 minutes" from the toolbar.

I tried using Window's System Restore to reset my computer to a restore point from yesterday, but this had no effect on my Firefox session. Is there any way to reverse this and recover the session I've been using daily since before Quantum had been released? Is it anywhere?

All Replies (20)

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Sorry to hear about that. I've never used the "Forget" feature so I'm just going to set that aside and focus on recovering session history data.

Could you start by making a backup of your existing session history files? Here's how:

Do not exit Firefox, or if you closed it, don't re-open it.

(1) To open your profile folder...

If Firefox is still running:

You can open your current Firefox settings (AKA Firefox profile) folder using either

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

In the first table on the page, click the "Open Folder" (or "Show in Finder") button.

If Firefox is closed:

Type or paste the following into the Windows Run dialog or the system search box and press Enter to launch Windows Explorer:


In that folder, do you see a semi-randomly-named folder? If so, click into it. If you find multiple such folders, find the one that was most recently updated.

(2) Copy out session history files

In your profile folder, double-click into the sessionstore-backups folder. Save all files here to a safe location such as your Documents folder.

(3) What files did you find?

The kinds of files you may find among your sessionstore files are:

  • recovery.jsonlz4: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
  • recovery.baklz4: a backup copy of recovery.jsonlz4
  • previous.jsonlz4: the windows and tabs in your last Firefox session
  • upgrade.jsonlz4-build_id: the windows and tabs in the Firefox session that was live at the time of your last update
  • various .js files from Firefox 55 or earlier

Could you take a look at what you have and the date/time of the various files to see whether you think any of them would have the missing tabs?

The files might be "as of" the Windows system restore data rather than more current. We can discuss how to look for more current files later.

To preview the contents of a file, you can drag and drop it onto this page, then click Scrounge URLs:

That tool is on my site, so please let me know if it doesn't work for you.

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Thanks for your quick reply, jscher2000. None of the files show my old session, unfortunately. They all have been updated to 11:59pm last night, and they all show the current session of tabs seeking a solution to this problem.

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Let's check for other profile folders. This is a copy/paste, so apologies for any discrepancies:

It's a lot of things to check, but if you go step by step, it's not too bad.

Did Firefox perform a Refresh?

Unless it was interrupted in progress, you should find a folder on your desktop named Old Firefox Data. Inside would be a semi-randomly-named folder (like a1b2c3d4.default) with freshly updated files. Do you see anything like that?

If so, we'll suggest how to rescue key files or completely restore the earlier profile folder.

If not...

Does the Profile Manager list other profiles?

To check on that, inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

This page should list all the profiles Firefox is currently aware of. If you see a profile that is not currently set as default that looks promising, scroll down to it and click the Set as default profile button below that profile, then scroll back up and click the Restart normally button. (There are some other buttons, but I think those are still "under construction" so please ignore them.)

Firefox should exit and then start up using the other profile. Is that the right one?

If it's not there...

Are there unlisted profiles?

Here's how to check whether there are additional profile folders in the standard location in addition to the one you're using. Start by opening your current Firefox profile folder using either:

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

In the first table on the page, click the "Open Folder" button, to launch a new window listing various files and folders in Windows Explorer.

In the Windows Explorer address bar, click the capitalized word Profiles to move up one level in the folder hierarchy. More than one folder here by any chance? Do the files in those folders look like they were last updated around the time of the update?

If you've got any promising looking folders, we can discuss next steps to recover use of them, and any session history files they contain.

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If your current profile folder does not have useful session history files, and there are no other current profile folders, you could try mining other restore points. Please do not use Windows system restore, as it can permanently trash Firefox data.

Accessing Shadow Copies on Windows 8, 8.1, and 10

(1) Set Windows to show hidden files and folders:

(2) Download and run one of these programs:

Within the most recent restore point shown in the program, you can explore along this path to see whether you can find a recent shadow copy of your profile:


(3) Within the seemingly most recently updated profile folder, double-click into bookmarkbackups sessionstore-backups and Export any recent files you want to check to a convenient location such as your currently live desktop (not the desktop inside the restore point).

Then you can inspect the contents of that file using the Scrounger tool.

Anything promising?

Accessing Shadow Copies on Windows 7

Open your current Firefox settings (AKA Firefox profile) folder using either

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

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Double-click into sessionstore-backups and right-click recovery.js > Properties, then click the Previous Versions tab

Windows should query restore points for older copies of this file, and you can use Copy... to back up the previous one to a safe location such as your Documents folder or Desktop.

(You also could check previous.js and other files.)

Then you can inspect the contents of that file using the Scrounger tool.

Anything promising?

Modified by jscher2000

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Hi jscher2000,

I didn't find any Firefox folders on my desktop even when I adjusted my settings to show hidden files, and unfortunately I have no other profiles.

Using Shadow Explorer I find many bookmark backups. The latest appears to be from the 30th of September. But my bookmarks were not affected in the memory dump, so I'm not sure if this can help me. I dumped one into your scrounger but did not see anything come up under Session History or Open Windows. I have included a screen capture so you can see what I'm looking at and whether I'm doing it right.

Please let me know if you have any further suggestions.

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Whoa, sorry, I copy/pasted different sets of steps. Actually, you should be looking for files in sessionstore-backups and I will update my earlier reply.

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Thanks jscher. Dropping any of the files from sessionstore-backups into the Scrounger shows one window and the first two tabs of the session that I lost. This is the only window that I care about, but I'm not sure if it is meaningful that only two tabs are displayed, or if this is meant only as a preview of the session.

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The Scrounger should show all the URLs it can find, so it's a bad sign that there are only two URLs. What about slightly older "upgrade" files in sessionstore-backups? Are those still available?

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One of the recovery files could not be read, but the rest only showed the two tabs. The oldest upgrade file shows three tabs, which is the most of the lot.

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I take it that it would be pointless to try to restore my session from these inexplicably incomplete backups. Is there nothing left to do?

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The Forget means exactly that Forget All your browsing history from your selected time frame is gone!!! You was so desperately for 5 minute of navigation so that you do windows restore? No! This feature affect only programs not documents, nor unsaved work. You search for your favorite Weather site in your recent history. You don't bookmark it? You don't remember it? Forget not delete your bookmarks. Nor your memory. This seems to me a Joke But you have a good sense of humor You make me smile :))

Have a good day!

Modified by AnnaSycamore

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I have cleared history under Options > Privacy & Security > History many times in the past without any issue. I mistook this new button to be a shortcut and an improvement since it allowed me to undo only the last 5 minutes. I did not notice in my tired state of mind last night that it would restart the browser with a fresh window, but that is no reason to expect it to have eliminated my entire session from the History menu, as well. I was not desperate for 5 minutes of navigation, I was desperate for several months' worth of tabs.

Jscher2000 should by all rights be on the payroll, but you, AnnaSycamore, are a perfect example of why volunteer support runs a risk to the reputation of the company. Your rude and ignorant remarks add nothing of value to the conversation.

Modified by wynden

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Hi wynden, if you save the JSON version of the data from the Scrounger page and open that file in a Firefox tab, it should appeared in a structured view where you can expand/close different windows and tabs from the file. Does that show more data than the HTML view? If so, then it sounds like something went wrong with the Scrounger spotting the separations between the tabs. It might be worth trying to restore that file, or mine out more of the URLs.

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Hi jscher,

I get an error when I try to save the JSON. Please see attached.

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Okay, it sounds as though the decompressed data has an inappropriate character at the 386,358th position in the text. It still seems like that's a lot of characters to only scrounge up two URLs. Either way, if it's not a valid JSON structure, then Firefox won't be able to restore it even if you sneak it into your profile folder in places of a file Firefox is looking for.

If you copy/paste the decompressed JSON from the box into a text document or Word document and start searching for "http can you find more URLs from your lost tabs?

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Sadly, no. There are 7 pages devoted to my Amazon Music tab, ~4 to my gmail and the remaining 99 pages all have something to do with my Facebook Messenger tab. Unless you have any other ideas, I'm presuming that I've reached a dead end.

I want to thank you, sincerely, for taking the time to help me in troubleshooting this issue. I deeply appreciate it, even though the effort ultimately proved futile. You are a knowledgeable and helpful individual who is easy to follow and understand, and you are a tremendous asset to this community.

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Thank you for the positive feedback, and sorry I can't think of anywhere else to look.

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If you use the Forget button then you close all open windows and create a new window.

You should get a warning.

Proceeding will:
Close all Tabs and Windows
Delete Recent Cookies
Delete Recent History
Open a new clean Window
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Cor-el, please see my reply to AnnaSycamore, above. Your post is redundant and references "recent" history. The issue is that "Forget 5 minutes" failed to remove recent browsing history. Instead it permanently deleted my complete session history which extended far beyond the past 5 minutes.

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I tried this "forget 5 minutes" thing in a test profile and:

  • when it closed the most recent tabs in the current window, it also closed the tabs that were also open longer than 5 minutes
  • it also removed all the session history files (in the test profile, I had previous.js from an earlier session a few days ago)
  • I could find and re-launch the missing pages from History (Library window), but that is extra work and in a real-life situation, it would not be easy to spot the ones you had kept open among the crowd

The way this was designed does not make sense for your original purpose of just trimming a couple items from history. Firefox definitely is destroying more data than necessary.

Edit: Added screenshots

Modified by jscher2000

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