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Restoring discarded tabs

  • 5 replies
  • 1 has this problem
  • Last reply by Ihmislehma

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After needing to do heavy maintenance due to a malware/malvertising issue that cropped up, I needed to restart and refresh Firefox a couple of times. While all the tabs are still present, they are now "discarded". I am fully unable to restore them, currently. Googling has not given me any real insight as to what is going on.

I did have Tab Suspender extension/app in use, so perhaps I should have disabled that and refreshed all the tabs. Impossible to say now, and hindsight is not exactly helping me restore any of this.

I have a lot of tabs, and I have managed to copy the titles of each tab, so I should theoretically be able to find each one again. However, if there is an easier method to restore all my tabs, I'd prefer that.

Any help would be greatly appreciated.

All Replies (5)

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How do you know the tabs are in a discarded status -- do you mean there is a physical tab, but its URL is missing and therefore it can't be reloaded?

If you haven't already, could you back up 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

Viewing File Contents

I have a tool to decompress the LZ4 files and extract a clickable list of links. I don't know what it shows for discarded tabs, so if you have the inclination, could you try and see whether it recovers the URLs either from the latest file or a previous one?

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How do you know the tabs are in a discarded status -- do you mean there is a physical tab, but its URL is missing and therefore it can't be reloaded?

If you haven't already, could you back up your existing session history files? Here's how:

I backed up everything before I reset Firefox - profile and all, and stored it outside any Firefox folders. Swapping to those did not restore the tabs, unfortunately. Pinned tabs are fine, which leads me to believe it was a bad interaction between Tab Suspender and whatever I did wrong/the restore.

My tabs physically exist, but the links appear scrambled or corrupted. I linked an image of why I call the tabs "discarded" - it's the information I get while hovering. As can be seen, the tab titles do remain properly.

As for the scrambled links, the link I'm hovering over should be But what I get is moz-extension://61a73bdf-7283-4ba8-ad5c-6d57ea2ec174/discarded.html?t=Kelretu%27s%20Modders%20Resources%20(WIP)%20at%20Skyrim%20Nexus%20-%20mods%20and%20community&

The link can actually be restored from here - I need to delete everything until I reach the www, swap every %2F to be a /, and delete everything at the end starting from the &. This "formula" persist through all links, but the sheer amount of tabs I had/have makes it an extremely tedious process. I made a mistake in my tab amount, I know.

As for the specific Tab Suspender I used, it was this one: Uninstalling and reinstalling did not help. All extensions were lost in the refresh, and that may be linked to what happened. It's my best guess, anyway.

Edit: Using your tool ends up with the same result, unfortunately. Added in a second image to illustrate. A few stray tabs were fine, but the vast majority showed similar results to the screenshot.

Edit edit: Seems this is a problem directly related to the Tab Suspender. After some digging, I found a report on their github on the topic.

I will seek to inform them of this having happened to me also, and hope they can fix the issue. Thank you for attempting to help me.

Modified by Ihmislehma

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The good news is, the real URL is embedded in there, you can see it just after u= in the long URL. But it's a bit tricky to excavate.

One way to restore the original links is to run a script against the links recovered by the Scrounger before saving the page. So after scrounging, open the Web Console in the lower part of the tab using either:

  • "3-bar" menu button > Web Developer > Web Console
  • (menu bar) Tools > Web Developer > Web Console
  • (Windows) Ctrl+Shift+k

Then paste the following script next to the caret (>>) and either press Enter or click "Run" to run it. Your first time, Firefox will ask you to type something to prove you understand it is dangerous to run scripts from strangers. That is true. After completing that task and deleting the test word/phrase, then you can run the script. What it should do is extract the true URLs and replace the extension URLs.

var suspended = document.querySelectorAll('a[href^="moz-extension://61a73bdf-7283-4ba8-ad5c-6d57ea2ec174/discarded.html?"]');
for (var i=0; i<suspended.length; i++){
	var fullurl = new URL(suspended[i].href);
	var origurl = fullurl.searchParams.get('u');
	suspended[i].href = decodeURIComponent(origurl);
	suspended[i].textContent = decodeURIComponent(origurl);

Then after the URLs are fixed, you can save the document.

As a footnote to anyone else reading, the "UUID" in the moz-extension:// URL is different in every installation of Firefox, so you'll need to modify the first line to the address you see on yours.

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You can find the UUID of all extensions in the extensions.webextensions.uuids pref on the about:config page (prefs.js), so if you have the extension installed then you can edit the key/value pair of this extension and change the value to the UUID you see in the links that show in the screenshot.

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Hey, sorry for the very long wait. Life happened and I was majorly distracted from relatively more minor problems. I was unable to replace the session itself, but the scrounged links work now, so I'm going to go through them manually. This is much easier than digging through the scrambled links, so you have my thanks. Thank you for being patient with me, this really saves me so much trouble.