Firefox Community Forum

new firefox update today plus windows update - get 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." Have tried to restore - no luck. Other bookmarks - empty.

Lost all bookmarks

Hello,

I received a popup tab about creating separate profiles. I am still not seeing an option to create another profile, in my case keep personal and work browsing separate on my work computer. The articles I have read do not seem to fit my situation. Firefox is up to date. Thank you for your help.

Do I have to be logged into an account to use profiles? I'm on my work computer on which I don't log into my account and "Profiles" option does not show up on my toolbar.

Hello, I have two profiles, one for work and one personal. I used two different email addresses for them. How can I merge these together for the new profile management?

I don't have a Profiles menu under the Account button on the main toolbar. My Firefox was just updated and the update tab info talked about the new profiles feature as if it was available. Is this rolling out in phases or should I be seeing it?

I have version 144.0, updated on 10/14/2025.

Thanks.

I am using a very old system that is running out of storage space. There is an 8.73 GB folder that I would like to empty to free up space. C:\dtemp\Profiles contains several folders that were created 10.27.21: 2qzfs15q.default, eybandys.default, f81zrqic.default-release, pctnmazu.default-release-1, and yns5cb3s.default-release.

Can I delete any of these folders?

The article explaining why one should not downgrade ignores a critical reason why one needs to downgrade and that is when it turns out that the new version breaks an existing website!

I got bitten by this when Firefox "upgraded" me to V143 after which point the ticket system I use to support my customers stopped working. That same ticket system continues to work fine in Safari, Edge, Chrome and Brave, etc.

Worse, when one does try to downgrade, the old profile gets removed which means you lose EVERYTHING you had (tabs, bookmarks and presumably all the settings and saved passwords, etc). You need to be keeping the old profiles around so that they can be accessed again should someone NEED to downgrade. Fortunately I was able to use Time Machine to recover the old profile --- but somebody just didn't think this through.

Much as I have loved Firefox over the years, I'm starting to feel that it's time to give up on it and move to something else.

Turning off automatic updates is not a solution because eventually one will choose to upgrade manually and most people won't remember to make a copy of their existing profile. Should one then encounter a problem, you're back to square one

Very disappointing .

I have my personal account on firefox and it syncs everything but I want to be able to do the same for my business account. when I sign out of my personal and try to sign in to my business it says I can't. I try to re-set my password and it says I have to use the "primary" account email. It does not accept my business account.

How do I get firefox account for my business email?

Thank you

This is Firefox 142.0.1 on Windows 10. I prefer to have a local copy of the Firefox profile saved to a USB stick as a simple backup and for copying to another PC if necessary. I have been doing this for years, but now I am unable to do so because Windows gives me an "access denied" error for all of the files in the top-level profile directory. I cannot even open them in Administrator mode. If I try to copy the profile directory as described in your help pages, it says that I need permission from the account that I am logged in as in order to access the files! I have been using Windows since version 3.0 and I cannot understand what Firefox has done to make the profile inaccessible to everything but itself. Obviously, Firefox is able to read the files without additional permissions, so why can't I?

I have 3 different profiles on my Desktop Firefox, and I'm able to change between them and even set some commands on CLI to switch between them easily, opening one or another.

Now, my question is: How can I do such a thing on mobile? I only linked my main account, and as far as I understood, I cannot link to multiple and switch on demand. Is there any way? Am I missing something?

I checked the tutorial on how to setup profiles and the profile manager doesn't seem to exist on mobile.

Thank you for your attention!

Could someone help me start over again and get it right, instead of a mess? Is it possible to somehow start from scratch or fix what I am doing wrong? Is there some way to open a new account and dump the mess I'm facing now?

Starting with Firefox 141, I noticed the profile folder is locked down by Mozilla by way of folder permissions, to the extent that I (as administrator) cannot even take ownership of the folder. Even after I completely uninstalled Firefox and restarted my computer I can't take ownership of the folder, nor can I delete it - access is simply denied. I have to literally boot up with a Linux Live distro to be able to delete it. This is invasive and NOT OK!!

I work with multiple profiles that require backups and be copied. I also have a 'master profile' which is set up to co contain all my settings and addons - when I require a new profile I simply copy it over and voila. Not even this is possible anymore, as Mozilla has locked down the entire folder tree, I can no longer copy a new profile into C:\Users\*USER*\AppData\Roaming\Mozilla\Firefox\Profiles.

I also cannot copy existing profiles (and therefore also not able to backup) out of C:\Users\*USER*\AppData\Roaming\Mozilla\Firefox\Profiles - access denied. This is uncalled for by Mozilla. I have complete removed Firefox from my computer, including registry entries, and even after that I'm still denied access and cannot even delete C:\Users\*USER*\AppData\Roaming\Mozilla.

The only solution to to any of the above issues is to either reboot into Windows Safe Mode or bootable media of another OS. But this is totally impractical - Mozilla cannot expect of me to stop all my work and restart my PC every time I need to perform any of the above mentioned issues.

This is highly invasive by Mozzilla - to not even be able to delete a profile folder without any trace of Mozilla on my computer???? Come on, FIX THIS !!!

Will Mozilla please provide the solution?

Firefox created a new Profile for me during a recent update and ignored the Profile I had been using for many years.

That probably occurred because Firefox couldn't find the original Profile. I had moved it to C:\0-FFox\ to shorten the length of file names. I had been getting File-Name-Length errors, which ended after moving the Profile closer to C:\.

Now I can't access or use the original Profile. I've researched the ins and outs of Profiles but can't find a solution to this problem. I want to add my old Profile to the new Profile created by Firefox and maybe switch between the two, or maybe revert to using only the old Profile. But I can't figure out how to do that. Adding a Profile seems to imply adding a new Profile and not an old one.

I sincerely hope you can help me solve this problem!

Many thanks! Wayne

Dear Mozilla team,

On my Firefox browser I can't see the icon for create new profile, even though I already updated it. Please check and fix it for me and other user. Thank you!