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Through extensive troubleshooting, I am unable to get firefox to open at all.

I've done a full uninstall, cleaned all user directories, program files / x86, program data, appdata roaming and local, etc. I used the Microsoft uninstaller and even Revo Uninstaller to remove everything related to Firefox, did a restart and reinstall of the latest one and it still won't launch.

Firefox was previously working until a reboot occurred and now it won't launch.

Firefox 32 bit seems to work when installed, and running Firefox as an admin previously worked but no it no longer does.

I looked at the following articles: - https://support.mozilla.org/en-US/kb/firefox-wont-start-find-solutions - https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles - https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed

There's no malware on this machine (business EDR on it, even disabled it as a test and it still didn't open).

I was able to launch the profile manager but now I am unable to as the processes launch in task manager and then within 5 seconds they close.

Firefox is not running in the background for any user (I'm the only one logged in after a reboot as well)

I'm unable to open in troubleshoot mode either. Tried run as and admin cmd "C:\Program Files\Mozilla Firefox\firefox.exe" -safe-mode

Ran SFC / scannow / DISM restore health commands as well and both came back fine / no integrity violations

I had a problem where FF 140.0 would not update, and in trying to get FF yo update, I used a re-install tool to which I was pointed in my problem report. This caused FF to wipe out my configuration, and I lost all my windows and tabs. I have gone to

    \Appdata\Roaming\Mozilla\Firefox\Proifiles\abnfpged.default

cleared all of the data therein, and restored that directory from a backup I made last Monday. But I cannot get FF to use that directory. "about:profiles" shows only two profiles, but the Profiles directory has five profiles:

03/10/2026 09:39 AM <DIR> qf00ka5x.default 03/10/2026 09:39 AM <DIR> v842ceue.default-release 04/11/2026 09:16 PM <DIR> .. 04/11/2026 09:16 PM <DIR> . 04/12/2026 03:08 PM <DIR> abnfpged.default 04/12/2026 06:29 PM <DIR> jdfj91sd.default-release-1775960183850 04/12/2026 06:48 PM <DIR> f1jq4mlq.default

Only the profiles beginning with "j" and "f1" are seen in the "about:profiles" screenshot I have attached. And I have attached a screenshot of my profiles.ini file. Also, in the abnfpged.default directory I restored, where is the list of all of my open windows and tabs? FF used to keep that in a sessionstore.jsonlz4 file, but that file is only written when FF closes. I tried to save a copy when I was having problems, but I stored the copy in the same directory, which FF changed during the re-install process. Here is my profiles,.ini file:

[Install308046B0AF4A39CB] Default=Profiles/jdfj91sd.default-release-1775960183850 Locked=1

[Profile1] Name=default IsRelative=1 Path=Profiles/f1jq4mlq.default

[Profile0] Name=default-release IsRelative=1 Path=Profiles/jdfj91sd.default-release-1775960183850

[Install641D10338ABA448D] Default=Profiles/abnfpged.default Default=1 IsRelative=1 Locked=1

[General]

StartWithLastProfile=1

Version=2

[BackgroundTasksProfiles] MozillaBackgroundTask-308046B0AF4A39CB-defaultagent=lnvi5jn5.MozillaBackgroundTask-308046B0AF4A39CB-defaultagent

I have not worked with the ;profiles.ini file in many years, as my FF configuration has not had problems. Thanks.

Good morning. I opened up Firefox this morning and all 4 rows of shortcuts were missing. I have gone into settings and made sure the settings for 4 rows was still the same. I cannot find them anywhere. Please help

The latest update 141.0 (64-bit) has changed my default save location from g.drive to users//downloads. How do I change it back to g.drive? I use Firefox synced between 2 computers (1 desktop and 1 laptop). I use google drive so that I can access the same information on both devices. I NEED screenshots to be saved in a specific folder in g.drive. How do I do this. Before this update, there was not this issue. Thanks in advance.

The other day I accidentally pressed a keystroke that changed a Firefox setting, and now it thinks I'm on a mobile device/displays sites in mobile view where possible by default. This has persisted despite restarts of the browser and the computer and has been happening since Sunday (Australian time). I've tried opening the Responsive Design dev tool and I've sent screenshots to a techsavvy friend (I'm totally blind and use a screen-reader, so couldn't tell this was happening until I tried to use a site that had a radically different layout in mobile view), and aside from not seeing an exit button or a switch to change device mode, he couldn't tell what was going on.

I'm stuck and need help! I would like to unmobile my Firefox!

Hello, When I view some pages with inline video graphics, I see a garbled video frame. I have attached a screen grab from part of one screen. I have no issues with YouTube or other videos. It's just the graphics of some webpages such as looking at an Apple product on their site. I have not had this issue using Chrome under the same conditions. It's like I have a corrupted Codec or something. Does anyone have any suggestions? Thanks.

I am a Cacti developer and we are considering switching from FontAwesome Web Fonts to Tabler Web Fonts. However, on Firefox for Windows only, we are having a major slowdown when using the Tabler SVG based webfonts. The page load is first stalled by Firefox apparently loading all the Web Fonts, which would appear normal with any browser (though exceedingly slow on Firefox for some reason).

However, once the page is loaded, when going off tab to another browser tab, and then back to the Firefox tab that includes the Tabler webfonts, there is a 3 second delay before the tab switches. When we enable the performance analyzer, we find that the delay is almost 100% Reflow of the page, even though the page is static as this point (no changes) from the last time it was activated.

We do not have this issue on Firefox for Linux, MS Edge or any other Chromium browser, only Firefox on Windows. I'm using the latest version 134. Should I be opening a bug?

I've freshly reinstalled Windows 11 and after trying to access and watch a movie on any of these sites I get an error (see the pictures).

Browser version: 137.0.1 (64 bit) Widevine version: 4.10.2891.0

Already tried to disable/enable DRM. Already reinstalled firefox. Already manually installed widevine. No clue what could be causing this issue.

Hello all,

I am currently testing the new VPN feature in Firefox. I Is noticed that Firefox always starts with this integrated VPN being off. I searched but I didn't find any way to have it always on when launching VPN. Is that possible?

Thanks!

My tabs crash all the time. Sometimes it'll go a while without crashing, other times it's literally every two seconds. Particularly if I'm doing anything that doesn't autosave. Thanks. Sometimes it's just whatever tab I'm on (or occasionally I'll click on one I've had open in the background only to discover it crashed at some point, other times (and not infrequently!) it crashes the entire browser. Sometimes when it does that, it also logs me out of everything for no particular reason as a little sadistic cherry on top. The passwords are still saved I'm just logged out of EVERYTHING. A few times, it seemed to have made my bookmarks go away, but force-stopping it and re-entering made them reappear, so they weren't deleted. I don't know what's going on but I'm at my wit's end. The crash reports mostly just say EXCEPTION_ACCESS_VIOLATION_WRITE (I haven't checked every single one individually since there's too many, but the ones I've clicked on all say that as far as I recall). If this keeps up I'm going to have to switch browsers or something because I'm actually losing it.

I prefer the tabs be below the bookmark bar, and successfully modified the CSS file to do this some time back. Now update 133 has once again pushed them up below the menu bar. What do I have to do to get them back where I want them this time? And why can't you just leave the tab location preference alone when doing updates?

Machine: Dell Inspiron 15 CPU: Intel i5-7200U @ 2.5 GHz OS: Ubuntu 24.04 LTS RAM: 16 GB GPU: AMD Radeon R5 M445

Yesterday I switched on my PC, opened Firefox and the home page was black. See the attached screenshot. This is not caused by some accidental switching on of the dark mode. Dark mode is clearly off. Neither can I adjust settings to make the Google home page revert to its customary light grey shade.

This isn't a big deal, I know. And it has happened before and in a short period gone away by itself. Maybe it is to do with a glitch in the latest Firefox version. But it has an unpleasant appearance and discourages surfing.

My Chrome Google home page doesn't have this issue.

Can anyone advise on how to fix this unwanted black screen problem ?

Hello. In the past two days I lose my tabs when I shut down Firefox. I used to be fine using the X at the top right and when I restarted the browser, all my tabs would still be there. Then they started going missing, so I started using the menu option to exit the browser. The tabs still went missing.

Then I noticed the square icon button on the extreme left and have discovered that Firefox has different windows, and that one of them (see attached image) has all my tabs in it, while the current window does not.

I cannot change Window 2 to be the current window. There is no obvious function on the page, nothing in settings and google is useless - I just get pages of discussion of how to tab between different apps on the desktop.

How do I make Window 2 the current window? See image.

Thank you

Since updating Firefox I can no longer connect to known good sites without getting "Did Not Connect: Potential Security Issue".

This includes U.S. government sites! For instance, try connecting to https://covidtests.gov/ .

Why completely block access to the site? Why can't I make exceptions or tell Firefox to accept the risk and continue?

Hello, Im using localized (Lithuanian) version of Firefox. Several updates back, Firefox started including russian and Polish in preferred languages by default. Personally i know how to remove those for myself. However, since im managing around 300 computers in a school. This starts to become an issue. In Lithuania we only have one official language. And when pages in a school start opening in foreign (russian) language this starts to be quite annoying. I would love to keep using Firefox but i need help.

I just tried creating a new profile in Nightly, and I received the "Approve sign-in to Firefox" email with a code, twice, but the profile page kept saying that my email bounced or something. Now it's saying it's locked.

I'm trying to log into this page: https://accounts.firefox.com

The sign up or sign in button doesn't work. The first time I click it, it immediately refreshes. I click again and nothing. On the 3rd click, it just spins for 30 seconds then goes back to being blue. This continues every time I attempt to click further.

I can login on this page just fine using Firefox on my android phone. I can also login using the Edge browser. Matter of fact, I had to use Edge so I could post this issue.

This is a completely fresh install of Firefox, on a completely fresh install of Windows.

Up until 2 days ago, I had no issues accessing my yahoo email accounts (sbcglobal.net through At&T) I had done nothing different re settings. I rebooted my modem and my computer several times. I deleted old history which I do several times a week anyway. I called AT&T support team but they just suggested logging on to another browser. So I tried Edge and was able to access the emails successfully. I even "refreshed" Firefox and nothing changed except I had to replace several quick links. I checked for updates and discovered my Firefox browser is up to date. My Android cell phone has no issues with the emails. I have one on Firefox browser and one with Chrome on my cell phone and no issues with either one. I have been using the same log in link for many years. I even explored the new way to log in called "Currently.com" for yahoo mail. Still won't work on Firefox. But it does work on Edge. I would prefer to continue using Firefox for browser but need to use Edge til I figure this out. Any suggestions would be greatly appreciated. (BTW wifi IS on and the connection for everything else works fine.

Here is the message I get when I try to log in: "Something's gone wrong We may be having trouble with your connection. Connecting your device to Wi-Fi could help fix the issue or try again later. If you were using an app, close this page. Otherwise, start over." Legal policy center Privacy policy Terms of use Accessibility Your privacy choices ©2025 AT&T Intellectual Property. All rights reserved.