I-Firefox Community Forum

I'm not exactly clueless, but I'm not an engineer. For some reason, I had three open Firefox/Mozilla browsers open on the taskbar but connected to one icon. Today, I've lost the browser with all of my frequently used sites, and tons of research, family, friends, World War II, finances, etc. The other two browsers had one tab, and maybe ten-fifteen tabs, respectively.

How do I restore the main browser?

Thank you for any assistance.

Hi customer service, please help me to restore firefox data & tabs before today. my firefox update this evening crashed & unable to restore. Million thanks

The new version of Firefox has been uploaded to my desktop withoiut any notification or communication to me. I have now lost all shortcuts and other data stored on my original Firefox, indeed, I have been taken back to the original as if I am a new user. I have used Firefox for many years. How do I retrieve all of the lost data from my old version? I am not a techie so please advise in simple step by step measures. Thank you. Regards Martin Forge

I just used CCleaner health check and when done all my bookmarks were gone. I've had CCleaner for years and never had this happen before (laptop). The troubleshooting list was unclear and did not correct the problem.

mozilla keeps closing out.When it does I lose all passwords and bookmarks.I'm not even home when this happens.This started when I bought a new computer which has windows 11.Old one had 10.When some bookmarks come back they are old one or the don't work

This is the message I get when I try to access my Bookmarks: "The bookmarks and history system will not be functional because one of Firefox's files is in use by another application. Some security software can cause this problem." I have already tried to find out from Microsoft if their latest reinstallation of Office Professional could have caused the problem. They say they have nothing to do with Firefox. How can I get my Bookmarks and History back?

I did reinstall of the Windows on all the devices I had, PC and laptop. Now I've lost my data bookmarks, password and sites. Please help me out how what I cab do here.

Several times now I've closed firefox while having the open previous windows and tabs on startup on only for all my tabs to have been closed (with this time in particular being annoying due to losing tabs that I needed to have the specific link for). Is there any way to restore tabs lost in this way?

your browser did an update on my windows 11 home version laptop and now I cannot access my bookmarks and have a message at the upper left side of my browser screen.....

Firefox updated and all bookmarks and history has disappeared. Is there a way to get them back?

Thanks, Scott

Moderator note: This question has been edited to correct the formatting.

Firefox crashed with many open tabs. I went to History > Recently closed tabs > Reopen all tabs, clicked. Nothing. The list showing only very few of the tabs I had open, but none of them are restoring anyway.

I lost all my bookmarks after the Nov 2025 update for Firefox. Couldn't find the backup file - not sure if Mozilla backed up the bookmarks before the update! If yes, please share path to find backup.

Today I closed Firefox as usual. It wrote recovery.jsonlz4 and recovery.baklz4. (Sorry if I’m missing some details, I’m just a bit upset.)

On the next launch, it didn’t show a window (most likely due to gWSL). I knew that after the next exit it would rewrite the session files, so I backed up .mozilla. (At that moment I didn’t realize recovery.jsonlz4 was already overwritten.)

I killed Firefox and WSL, restarted, restored .mozilla, reopened Firefox — and it rewrote recovery.baklz4 with an empty recovery.jsonlz4. The session page showed nothing. I panicked, because my previous .mozilla backup is very old.

I found out there may be a way to recover if I don’t launch Firefox before copying recovery.baklz4 to recovery.jsonlz4. So I closed Firefox, restored .mozilla again, checked that the .baklz4 file was larger, copied it over the .jsonlz4, and opened Firefox. It successfully restored everything.

Why do I need to manually back up session files? Could they be versioned, or at least not replaced by an empty session?

If the only tab is about:sessionrestore, that usually means something went horribly wrong, and it shouldn’t overwrite the previous session.

Relying on third-party extensions doesn’t solve the problem. Replacing a valid session with a blank one leads to data loss.

As you probably understand, this isn’t the first time I’ve lost data because of this behavior. This time I managed to save it, but previously I didn’t know these steps and lost my tabs.

Dear Support Team,

I am writing to request assistance with an issue I encountered after a recent Firefox update. After opening the browser, an automatic updat led to making all of my bookmarks, saved passwords and website data disappear. The profile I was using had been active for over two years and contained important information that I now cannot access (it wasn't a profile I created myself, I just used the browser normally).

I have already tried several troubleshooting steps, including restoring previous profiles, checking the profile folder, and attempting to recover data from backups. Unfortunately, none of these attempts have been successful so far. The about:profiles website tells me my old profile does not exist but in my Firefox folder, there is a (profile?) folder from 2023 which contains only one file.

Could you please help me recover my previous Firefox profile or guide me through any additional methods that might allow me to restore my lost data?

Thank you very much in advance for your support.

Kind regards, Sophia