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Crash > Tabs vanished > Could not re-open via "Recently Closed Windows"

Firefox Recover data
Andrew Mabon replied 15 minutes ago
Andrew Mabon
Andrew Mabon

I had 1600 tabs open (foolish, I know, but 16GB RAM and have had no problem with it in the past) when the app suddenly stopped responding.

Restarted the app, all tabs were gone, replaced by my starting page. Very strange, as I have the setting to re-open previous tabs per default. Attempted to open via "recently closed windows", saw all of the tabs, but the content never loaded in - I was able to resize the window, but could not add new tabs or close existing ones with either mouse input or keyboard shortcuts.

The app became unresponsive again. Restarted the app, did the same thing, had the same issue. This time, it caused the entire computer to become unresponsive. When I started the computer again, opened FF, it was on the start page, and the option of "recently closed windows" was suddenly greyed out.

Following the online guides, it takes me to C:\Users\Username\AppData\Roaming\Mozilla\Firefox\Profiles but there are very few json files in there and only from a few minutes ago. There is nothing in there from before the crashes

There are no Windows previous versions to restore from

1. Is there any way to recover the tabs that I have missed? 2. Why is information about tabs not stored in a non-replacing way locally? 3. Why is information about tabs not stored on the account in a better way? I am far from the only person who uses tabs as a form of storage, even if it is not optimal

I had 1600 tabs open (foolish, I know, but 16GB RAM and have had no problem with it in the past) when the app suddenly stopped responding. Restarted the app, all tabs were gone, replaced by my starting page. Very strange, as I have the setting to re-open previous tabs per default. Attempted to open via "recently closed windows", saw all of the tabs, but the content never loaded in - I was able to resize the window, but could not add new tabs or close existing ones with either mouse input or keyboard shortcuts. The app became unresponsive again. Restarted the app, did the same thing, had the same issue. This time, it caused the entire computer to become unresponsive. When I started the computer again, opened FF, it was on the start page, and the option of "recently closed windows" was suddenly greyed out. Following the online guides, it takes me to C:\Users\Username\AppData\Roaming\Mozilla\Firefox\Profiles but there are very few json files in there and only from a few minutes ago. There is nothing in there from before the crashes There are no Windows previous versions to restore from 1. Is there any way to recover the tabs that I have missed? 2. Why is information about tabs not stored in a non-replacing way locally? 3. Why is information about tabs not stored on the account in a better way? I am far from the only person who uses tabs as a form of storage, even if it is not optimal

All Replies (2)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 25 Contributor

Let's start with recovery and set the philosophical questions aside for the future.

When you checked the Profiles folder, how many individual folders did you find? Typically you would expect:

  • abcd1234.default
  • 1234abcd.default-release

Where that first 8 characters is randomized. The .default folder generally isn't used, so

.default-release\sessionstore-backups

is the most likely place to find current files. Please back up what you find here to a safe location so that, as you note, Firefox won't overwrite them.

If you have other individual profile folders, please check their \sessionstore-backups folders as well.

Very often during an automatic update, Firefox will create a snapshot of your tabs in a file named similarly to:

upgrade.jsonlz4-'20261102144711

(The part I bolded should indicate the release build.)

Can you find anything recent?

Andrew Mabon
Andrew Mabon Question owner

My Profiles folder looked strange following this debacle.

I had one with a string of letters and numbers.Profile1 Another one was string.default-release, but that one only had a "storage" folder and a "parent.lock" file.

Profile1 seemed to have more information. Went through every file in its sessionstore-backups but none of them had the missing data unfortunately (using your URL scrounger tool I was unable to find them).

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