Firefox Community Forum

At random times when opening the browser, all my tabs (except the first one) turn into about:blank. Relaunching the browser does not resolve the problem, and there is nothing in the history that allows me to restore them. It is extremely frustrating, as this is the third time I have lost all my tabs.

Hello Mozilla Support,

I need help recovering my old Firefox Sync data.

I recently formatted my C: drive and installed a fresh Windows installation. My old Firefox profile and local data were on the previous Windows installation.

After reinstalling Firefox, I signed into the same Mozilla account, but I could not find my old Recovery Key. I therefore used the option indicating that I had forgotten/lost the Recovery Key and I reset my Mozilla account password. I was then given a new Recovery Key.

After completing the password reset, I found my original/old Recovery Key.

Unfortunately, I no longer have the old Firefox profile because the C: drive was formatted, and I do not have another device containing the old Firefox data.

I still have the original Recovery Key.

Is there any possibility that my old encrypted Firefox Sync data can still be recovered using the original Recovery Key, or is there any way to restore the data that was associated with my previous Sync encryption key?

The data is very important to me, especially my saved passwords and bookmarks.

I understand the security requirements and can provide any information needed to verify ownership of the account.

Thank you for your help.

Somehow I got signed out of my account (no idea how). I've reset the password using the account recovery key. You sent a new recovery key but I seem to have lost that before I could save it.

My bookmarks disappeared and I don't have a restore option only an import from another browser but my bookmarks were saved on Mozilla Firebox prior to the recent upgrade of the Firefox browser.

I usually have a lot of tabs open (which probably isn't a good habit), but many of them are important to a project I'm doing currently. Usually if my imac Ventura 13.7.2 shuts down on it's own, or I have to shut it down because it's frozen, either I will have the option to restore the session, or if not I will have the option to go to "history"/recently closed tabs". But this time Session Restore showed up blank, "recently closed tabs" was greyed out or wasn't there, and "recently closed windows" is greyed out. In the meantime I've been using a new Firefox window and have a few new tabs, and that's all "recently closed tabs" will show. Not the "many tabs" from the session before.

It may be that this problem occurred after our most recent update a few days ago. (We're now at 156.0 (64 bit). Or I might have closed the Firefox window myself by mistake, instead of a shut down. Is that what caused it? Ugh.

I am not a savvy user at all, so the articles were way too confusing.

I am grateful to anyone who can explain a straight forward solution.

Thank you, Ellen

i get the message "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 tried all the help i can find and gone through Gemini AI recommendations and i am still left with a purple circle with a plus sign in it. Repaired Firefox and no change, removed Firefox and re-installed no change.

Hello,

I keep running into an issue where my group of saved tabs disappears.

I will make several groups of tabs. When I right-click and press "save and close group," to shut down my laptop completely. There are many times when I return and try to access the saved group of tabs using the drop-down arrow at the top of the browser; all the saved groups will be gone.

Normally, I find them under "Recent Tab Groups". There have been many times when they are completely gone. Is there another way to find these groups of tabs or are they disappearing completely are a certain amount of time has passed?

Thank you,

So every time the browser crashed or a blackout happens and it forced closed (sometimes the browser is closed normally and it still happens) the next time i start the browser it would show the restore session page. Pressing the restore session would just restore the open tabs and not the tab groups. Because of this i would need to go to the file manager, copy the previous.json and change it to replace the sessionstore. it's kinda annoying. is this problem just me or is this a known issue? also how to fix.

I am having an unusual problem with my main Firefox profile on Windows 10. The affected profile is:

C:\Users\Adam\AppData\Roaming\Mozilla\Firefox\Profiles\2giwv8i8.default-release-1746901618396

Firefox reports that this profile contains a user.js file. I cannot read, rename, move, modify or delete this user.js, even from an elevated Administrator CMD or PowerShell session. Attempts return “Access is denied.”

The unusual part is that Windows permissions appear correct. icacls shows my user account, SYSTEM and Administrators all have Full Control. The file is not encrypted, is not read-only, is not a reparse point, and Firefox is completely closed when I test it.

I also tested writing a new file directly into this Firefox profile directory and receive Access Denied. Other older Firefox profile directories on the same NTFS drive are writable, so the behaviour appears specific to certain Firefox profiles.

I have already performed a Firefox Refresh/reset, but the problem remains and user.js is still present.

I am investigating this because I am also experiencing unusual behaviour specifically with this main Firefox profile when using YouTube. Other Firefox profiles do not reproduce the same behaviour. I therefore want to completely eliminate any persistent profile configuration as a cause.

Can someone explain:

What could prevent access to an entire Firefox profile despite NTFS ACLs showing Full Control? Can Firefox, Firefox Sync, Enterprise Policies, an extension, or another Firefox mechanism protect or recreate user.js? Why would Firefox Refresh leave or recreate user.js? Is there an official/safe way to identify which preferences are being loaded from user.js when Windows itself refuses access to the file? Is there a way to reset all non-default preferences in this profile without losing bookmarks and saved passwords?

I can provide about:support, about:config, profiles.ini, ACL output and other diagnostics if required.

I would particularly appreciate advice on diagnosing why the profile directory itself returns Access Denied despite Full Control, rather than simply creating another profile, because I would like to identify the underlying cause.

I transferred my FireFox files from my older model macbook pro to this macbook air (M3) and maintained/used the FF3/oes daily. I installed the latest update, Tahoe 26.7, before shutting down my computer last night and this morning I discovered that my FireFox windows and tabs had disappeared, completely. Can these files be recovered, and if so, what are the steps?

Had to restore entire backup image of C: (boot) SSD that was saved on an external USB drive. I had been using FF 156, but the image restored FF 155. My FF profile is always stored on D: (internal HDD).

I launched FF and got a message that my profile was created with a newer version of FF and might not be compatible. The only option was to create a new profile or exit. I created a new profile but when FF opened I had no direct access to my existing profile on D: HDD. It wasn't listed when I clicked the Profiles button on the toolbar.

Came across a site that said to run Start>Run>firefox.exe - P. A box opened that listed both the newly created profile and my existing one on D: HDD. I selected the profile on D: and FF launched without any problems - everything fully restored. So if the existing profile is compatible, why was it so difficult to select it?

How 'bout this..? When FF detects that an existing profile was made with a newer FF version than currently running, why not give the user the option to install the latest FF update on that same message screen, in addition to the option to create a new profile? Then just relaunching FF after the update should allow an existing profile to be selected/used. Obviously existing profiles are compatible with FF updates since everything still works after routine updating.

Exact same thing happened with Thunderbird after reimaging C: because an older version was restored. I tried running thunderbird,exe -P without knowing if that would even work, and it easily allowed me to restore all 5 of my mailbox profiles with thousands of emails that are stored on D: in seconds.

Please make things easier...!

When I was running a game and updated my graphics card driver, Firefox was running in the background. My PC went completely black and became unresponsive, so I had to force‑restart the computer.

After rebooting, Firefox reverted to a brand‑new fresh‑install state. All my browser settings, login status, local profiles, browsing sessions, hundreds of open tabs and my categorized tab groups disappeared, only the welcome startup guide showed up.

I logged into my Mozilla account on my Android Firefox device. Some browsing history was synced back. However, synced history cannot restore the original tab session back‑forward page history, nor my manually sorted tab groups. All browser preferences, theme and language settings are also lost.

I originally had 4 separate local Firefox profiles on this Windows computer, isolated from each other for different work purposes. Only one profile was logged‑in to my Mozilla account and could partially sync data. The other three local profiles are completely gone. Those extra local profiles were NOT signed into any Mozilla account and were never synced to cloud storage.

In my Mozilla account’s connected devices list, there are two entries both belonging to this same computer: “MARSHAKK” and “Firefox by Administrator on MARSHAKK”, which correspond to my Firefox instance before and after the crash.

I cannot understand the community help articles about session recovery, and I’m unable to locate or restore my old local Firefox profiles and lost tab sessions by myself. Please give me assistance.

I had 5 tab groups and all of them vanished when I reopened my Mozilla today. I have tried to re access but all in vain, is there a fix on how I can regain my tab groups. I use windows 11

After problems with loading the current Firefox session, I seem to have retrieved my bookmarks (I cannot be certain all of them are there), except the Bookmarks toolbar and Other bookmarks folders are empty. I have a recent backup, but when I try to import the json file, it wipes out all bookmarks - I have to reboot to see them again. If I had them in html format I might try to manually add the missing bookmarks. Even better, maybe there is a way to merge the current and backed-up bookmarks. But I don't want to make things even worse. Any advice that certainly will work? Thank you for your help. Incidentally, sometimes the bookmarks won't load, and I have to reboot, sometimes several times, to see them again. How might I avoid this?

I use Firefox under Fedora (I'm two OS versions behind, must upgrade soon). I open very many tabs each day then work through them, theoretically every day, in practice they accumulate and I deal with them when I can. I rely on the tabs loading correctly on restart, but today they didn't, instead the set of tabs that were opened a few days ago loaded, and I lost everything I had done since then. Is there a way to retrieve the tabs that were opened just before this happened, ie around 15-20 hours ago? Ideally, again, I would merge them with the current ones, but reopening the old ones would take much much longer than reopening the new ones. Thank you for any advice.