Firefox Community Forum

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

Firefox 146.0.1 crashes every time upon launch (basically fails to launch), even in troubleshooting mode, with exception code 0xc0000005. Prior to today, it was working fine. Windows does not show any updates made over the last couple of days. I am on Windows 11 25H2, and I'm current with updates. Chrome works. Edge works. I logged on to the same computer as a different user (different profile folder in the user AppData folder) and Firefox still does not work. I tried to refresh Firefox and that did not resolve the issue. I tried to uninstall and reinstall Firefox and that did not resolve the issue. I tried to run DISM and SCANNOW and that did not resolve the issue. No issues are detected with a virus scan. I am stumped - please help!

Hello,

i was trying to check my apparmor stuff because of the warning on Linux. Now i tried duck.ai to instruct me , but created more damage than anything else. It said to set firefox in enforcement mode, now it wont start (well im using Firefox right now in complain mode)

How do I fix this problem that everything runs normally and safe?

Please help me! madmorph666@madmorph666-E14301:~$ sudo aa-complain /usr/bin/firefox /usr/bin/firefox wird in den Complain-Modus versetzt. madmorph666@madmorph666-E14301:~$ firefox ATTENTION: default value of option mesa_glthread overridden by environment. [Parent 72019, Main Thread] WARNING: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed [Parent 72019, Main Thread] WARNING: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed [Parent 72019, Main Thread] WARNING: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed [Parent 72019, Main Thread] WARNING: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed [Parent 72019, Main Thread] WARNING: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed [Parent 72019, Main Thread] WARNING: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed [Parent 72019, Main Thread] WARNING: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_widget_get_clipboard: assertion 'gtk_widget_has_screen (widget)' failed [Parent 72019, Main Thread] WARNING: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(firefox:72019): Gtk-CRITICAL **: 03:12:17.894: gtk_clipboard_request_contents: assertion 'clipboard != NULL' failed ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. [Child 72430, Main Thread] WARNING: Unable to open /var/lib/flatpak/exports/share/dconf/profile/user: Keine Berechtigung: 'glib warning', file /builds/worker/checkouts/gecko/toolkit/xre/nsSigHandlers.cpp:201

(/usr/lib/firefox/firefox-bin:72430): dconf-WARNING **: 03:12:53.181: Unable to open /var/lib/flatpak/exports/share/dconf/profile/user: Keine Berechtigung ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment. ATTENTION: default value of option mesa_glthread overridden by environment.

Hello, When I went to launch Firefox after starting up my PC this morning, I was greeted with: "Your Firefox profile cannot be loaded. It may be missing or inaccessible".

I went right to the Mozilla forums and found the help page [https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing...] . In this article it detailed how I should go into my AppData, then Mozilla, then Firefox, and look to see where my profile.ini file is. My profile.ini file was there, alongside the installs.ini and a few other folders. I attempted also to launch the profile manager using run and the "firefox.exe -P" command, but I got the same profile error as when I tried launching the app. The help page then recommended deleting the profile.ini file and then launching Firefox to hopefully remake the default profiles.ini file and enable me to launch Firefox, so I attempted that. When I tried relaunching Firefox, the profiles.ini file did not re-appear in my Firefox folder.

I then tried deleting the Firefox folder itself, and relaunching Firefox. This resulted in it being remade, but with just 2 folders left: Crash Reports and Pending Pings. Obviously that's not ideal, so I right clicked the Firefox folder and used the Windows "Previous versions" feature to restore the Firefox folder to a backup of how it was this morning. I then re-tried launching and I still got the same missing profiles error message. I also briefly attempted manually making a new profiles.ini file with notepad, and pointing it towards my Profile withing my Profiles folder, but that still resulted in the same missing profiles error.

This is basically where I am at now. I have confirmed that I do in fact see my actual profile in my "C:\Users\****\AppData\Roaming\Mozilla\Firefox\Profiles" folder, and as far as I can tell my profiles.ini file correctly points towards it. I did another reset of my Firefox folder to a backup of where I was at this morning before attempting anything. I can confirm my Windows account (Admin, and only account on the computer) has full read and write access to all Folders and files within the Mozilla folder, although I will mention some of the files in the Firefox folder were marked with the "Read-Only" attribute (not sure if that matters, but I tried unchecking those and still no luck)

As far as I can tell I have thoroughly exhausted all the easily accessible tips on the internet for solving this, so I am wondering what to try next?

TLDR: Error: Your Firefox profile cannot be loaded. It may be missing or inaccessible" Already Attempted (And failed): -deleting and prompting a remake of the profiles.ini folder -using firefox.exe -P to launch Profile manager -deleting Firefox folder to prompt a remake of that -multiple uninstalls and reinstalls of Firefox -manually remaking profiles.ini file after it didn't come back after deletion

Will link images of (1) profiles.ini file. (2) Profiles folder.

Every so often for the past few days this "unfinished" program window has appeared on my pc on top of a normal Firefox window (see attached png). Does this have something to do with Firefox? I think the same thing appears when I first open Firefox, then it gets "filled in" and appears as a normal Firefox window. I am running Firefox 133.0.3 (64-bit) on Windows 10 Pro Version 22H2 build 19045.5247 Windows Feature Experience Pack 1000.19060.1000.0.

Today, I signed on to use my laptop, as usual, nothing different about how I sat down or anything, and I try to open Firefox and it flashes something on the screen, but I don't catch it as it immediately closes as well. It looked like a popup with a button, if that helps. I then try to open it again, realizing that I've got that bug, the one that causes browsers to open for a split-second and then close immediately, so I try to fix it how I fixed Opera GX before I stopped using that. Restarting? Nothing. Looking online for answers? Found some! I try starting it in Troubleshoot Mode, I can see down in my taskbar that Firefox is trying to open in Troubleshoot Mode but isn't. Okay, let's try something else, the Profile Manager. I use the Windows+R key to open the Run window and type in firefox.exe -p which according to a couple of websites, -This one included- should have opened the profile manager in a popup, but all I get is a flash of a window and nothing else. Then, I finally try uninstalling and reinstalling the app, upon reinstallation it asks if I want to keep my settings and whatnot, I say yes, problem persists. I uninstall and reinstall again, only this time declining the ability to keep my settings, the problem persists.

I'm extremely confused as to why nothing is working, and I don't want to have to reinstall Windows itself like I saw a comment on Reddit recommend, so if anybody has a slight idea of a solution, I'd be grateful, thank you in advance.

Edit: Just tried downloading and running Chrome, it worked for a second until it randomly closed, I know this isn't the support site for that browser, but I thought I'd mention that the "Not opening, just falshing for a millisecond" isn't just a Firefox thing for me.

Can’t launch Firefox 3.5.19 on Linux Ubuntu When trying to run with:

./firefox

Terminal gives the following:

./firefox-bin: error while loading shared libraries: libdbus-glib-1.so.2: cannot open shared object file: No such file or directory

Hello! I am an avid user of firefox (especially with adblockers) on a windows 11 PC. Unfortunately, I have recently been experiencing an issue where when I attempt to open firefox, a window will open for a split second before instantly closing again. My PC is up to date, I have tried refreshing firefox and doing a clean install, but cannot seem to overcome the issue, or even open it in safe mode. Does anyone have any advice? Many thanks in advance!

I am having Firefox crash on startup much like Firefox Desktop crashing on startup, initially in version 140, but I have downgraded to version 139 in my troubleshooting and I'm getting the same symptom.

It is frustrating that this does not seem to leave any records in the Windows event log or the Firefox crash reports, and that the fact that there's a known issue of this severity is rather hard to find.

Greetings Ya'll,

I have to apologize if this is a double post, but I came back to the forum, & wanted to see if there were any responses, but i could only find my post listed under "My Profile"/"My Questions".

My original post was made Dec. 19-2025

=======================================

Early this morning as I went to use the Firefox browser, on My Desktop, I got an update, & then firefox opened, somewhat.

The homepage did not fill in with favorites, suggestions, etc, and in fact all that did load was the Search bar, but not one of my usual website buttons. The "edit", "help", etc. buttons at the upper left hand corner did load, but that is all. Not one of the buttons work, nor can I close out the Firefox page, by tapping the "X" in the upper right hand corner.

The only way that I could close out the "Firefox Page" was by going through the "Control/Alt/Delete" & then "Signing Out", which would initiate a "Re-start". Once I signed in, I could return to the Desktop, where everything works.

I use Firefox as my Browser on my Android phone, & at this moment, I've not had any problems using Firefox on my Cell Phone.

The only way that I could get to the Mozilla Website was by using the Microsoft Edge Browser, which is not giving me any problems as far as accessing the Internet!

How can I correct this problem, & go back to the Firefox Browser?

Hi people,

I have used Firefox for years but after the latest Microsoft Update it no longer starts or runs. Another product, Libre Office, also failed at the same time and I have been unable to resolve that problem either.

I have uninstalled Firefox, downloaded a fresh copy from the Mozilla website and reinstalled it a couple of times but when I click the desktop shortcut nothing happens. I can right click the shortcut and select the "run as administrator" command and something like the Firefox browser opens but all my shortcuts are out of date on it and the browser will not access anything on the net.

I also use Mozilla Thunderbird as my email providor and that is still functioning normally.

Is this some monkey business from Microsoft, a fault in Firefox or a fault somewhere in the inner workings of my computer?

Kindest regards, Colin Ballard, 23 January 2025

Hi, We are using Horizon VDI terminal server. Firefox is installed on these servers. Some users get Firefox is already running but is not responding error. Ending Firefox via task manager does not work. I log off the user and have them log in again, but it does not work.

When I check, I see that the user's profile file cannot be created on any terminal server.

Is there a solution to this problem?

Hi, I just want to tell the support that new version, 144.0 on 9th October 2025, has some glitch on my HP Chromebook 11 G5 EE. It will auto close when I try to open the Mozilla browser. So, I have to uninstall 144.0 and install 143.0 version which does not have issue auto close on my chromebook. Please look into this. Thanks.

I am still using Win 7 but converting to Win 11. The most recent "patch Tuesday" update from MS killed Office 2016. Since then Fire Fox will occasionally pop up the "Couldn't load XPCOM." (no file extension) warning. It may do this when opened but not always. Can also occur in the midst of a session.

Program seems to be working correctly but some of my pinned locations disappeared when this started. New locations are retained between sessions. Is there a problem with continued operation with this warning? Is there something that I can do to repair it.

Howard Neuschaefer [email removed]@sbcglobal.net

Is there a way to make the URL high lighting of the domain more obvious? I find that most people can barely see the highlighting and I'd like to make it obvious (bolder and red, or highlighted in yellow, for instance.)

Can this be done via userchrome.css?

Thanks,

Thane

export GDK_BACKEND=x11 MOZ_ENABLE_WAYLAND=0 MOZ_DISABLE_WAYLAND=1; /mnt/bootdrive/firefox3/firefox/firefox -P tx1p72s0.dev-edition-default XPCOMGlueLoad error for file /mnt/bootdrive/firefox3/firefox/libxul.so: /mnt/bootdrive/firefox3/firefox/libxul.so: undefined symbol: gdk_wayland_device_get_wl_seat Couldn't load XPCOM.

Has support for X11 been removed?

When I try and open Firefox, a window pops up for a millisecond before going off my screen, and firefox doesnt open. This is extremely irritating as i downloaded firefox since I also cant open chrome. Is there a fix to this, I have restarted my computer and have uninstalled and reinstalled firefox.

Thanks, Nathan

Firefox keeps crashing on my laptop I've had it run very successfully on the same laptop the first time i installed it it crashed the same way it does now but one day it randomly worked and continued working for about 9 months however at some point it crashed and i deleted it and reinstalled many times at best i have downloaded it and have managed it to run for about 10 minutes then closed and failed to load properly now it fails to launch completely at worst it doesnt run at all .i have tryed downloading it from the microstoft store and your website this time i downloaded it from Microsoft please help!