Diễn đàn hỗ trợ Firefox

I have an account with Chewy. When I try to access the link to "My Pet" I receive this message:

400 Bad request Your browser sent an invalid request.

I don't understand why or how to correct it.

Hi - Firefox placed an 'Old Firefox data' folder on my desktop and I am unable to delete it. I'ver tried third party apps, logging in as administrator, command line delete, uninstalling FF but am still stuck with it and my network settings are wrecked so I can't re-establish connection to the internet on that machine. Anyone with any suggestions as to how I get rid of the 'Old Firtefox data' folder ? Many thanks...

I opened up Firefox just now to find that my two profiles currently in use are completely inaccessible. I was faced with a "Create Profile" dialogue that launched me into a brand new profile with none of my settings, keybinds, cookies, extensions, anything. Despite this, I know for a fact that my old profiles are *still* there. As you can see my profile folders are right there, with all their data intact as far as I can tell from inspecting their contents, yet they are not accessible from the about:profiles.

Please help me. What is happening with the profile manager? How do I access those old profiles?

When i upgraded Firefox my old profile doesn't show up now. I found my old profile under about:profiles but when i click on the Launch profile in new browser i get this message, "You've launched an older version of Firefox. Using an older version of Firefox can corrupt bookmarks and browsing history already saved to an existing Firefox profile. To protect your information, create a new profile for this installation of Firefox" I did create a new profile but how do i get my old saved data, add ons etc to the new profile?

For highly encrypted messages and sensitive information each time renewed or discovered for the first time cam be very intimidating for certain people. Based on the facts and past experiences, this has become extremely important to discuss and share knowledge with true and trustworthy people only to ours and others peace of mind and safety.

I recently reinstalled Debian 13 on my workstation. This included installing Firefox-esr from the Debian repositories so the version before and after the reinstall is the same. Despite this, Firefox refused to start until I created a new profile - insisting that my profile was from an older version.

To add insult to injury, it offers a method to import data from Chromium (which I use rarely) but not from a previous Firefox profile.

Firefox Sync works so far as it goes, but not everyone wants to use it. Importing from a local profile should be easier to implement than remotely syncing - especially given that Firefox clients may not be the same on different devices.

And, of course, the initial point is that Firefox should accept a user profile when it was created by the same version. After all, when I upgrade Firefox on Debian, I'm not required to create a new profile. Why should I be forced to do it when I reinstall the same version?

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 regularly back up my profiles folder (desktop running Windows 10) and observe a steadily-increasing number of files. Where/what are they? If cookies, I really don't want to delete all cookies, but neither am I interested in manually going through the list and deleting individual ones. I realize we're not talking about a major storage space issue (~ half a gigabyte) -- just curious.

Hello everyone,

I’ve been using Firefox for 5 years now and I absolutely love it. I recently bought a new laptop, but I’ve run into an issue. On my old laptop, I was able to use multiple Firefox profiles at the same time—similar to how Chrome handles profiles.

On the old setup, when I clicked the three-line (menu) button, I could see my second profile there and switch between profiles with just one click. After installing Firefox on my new laptop, I can’t find that option anymore.

I know some of you might suggest using about:profiles to switch profiles. Yes, I’m aware of that method, but I find it inconvenient because I’d have to type about:profiles every time, which is a bit of a time waste for me. I really want the same quick-switch option I had before.

How can I get that functionality back? Any help or suggestions would be greatly appreciated!

I’m already using the latest version (142.0.1, 64-bit).

Thanks

I am tired of this bullshit.

So i was using the beta branch of the firefox and beta version stopped working with a site for some time. so i tried to come back to the stable version.

After i do that and fix my config. In every couple of hours there would be a notification window pop up with sound saying this

"firefox this profile was last used with a newer version of this application. Please create a new profile"

So i did create a new profile BUT i copy pasted my own configuration.UI stuff from my old settings from "About:config"

This notification STILL comes up FFS what do i need to do then?

HOW COME MY UI CONFIGURATION TRIGGERS THE DAMN NOTIFICATION?

I will not re-do my fckng UI configuration by hand.

hej, you write oh dear, no print is possible :-((( but you write to me, that I have win10... but it is a new machine with win 11...and firefox does not work, i cant se my mails?!?!!?

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?

Every other day, I open FireFox and may get the following error: XULRunner - This profile was last used with a newer version of this application. Please create a new profile. Also, this error may come up while I already have had FireFox open for a while. Once this error comes up, I check the version, and sometimes the version is older than what it was, meaning, FireFox reverted back to an older version on it's own. I created a new profile, but the error comes back. I removed FireFox and all folders, and the error still comes back. There is nothing I can do to stop the error from showing up again. See attached images. I am on Windows 11 23H2, all windows updates caught up, and the current FireFox browser version is 138.03.

I am trying to set up a profile however when I click the account icon the profiles menu item does not show up like it says on the manage firefox profiles guide. I am updated to latest firefox version.