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Firefox will not open on my MacBook Pro. Mac OS 15.5.

Terminal report: 2025-06-04 10:47:20.009 firefox[2076:19473] Server doesn't exist or doesn't provide correct selectors.

Behavior: Clicking Firefox to open results in a window asking for permission to install a new Helper tool. If I grant access I soon see a new window that says the Helper has been installed and I can go to my settings and manage it. Meanwhile the Firefox icon keeps jumping up and down and won't finish opening so I have had to force quit. If I do not grant access to the installation by clicking "cancel" I get the same result: Firefox dances and won't open. I have tried simple solutions like force quitting the dancing icon and restarting after getting the "installed" message. No difference. No difference also if I cancel the installation, force quit and restart.

Please help!

Whenever I close Firefox and try to reopen it, it brings up a system error that says, "The code execution cannot proceed because C:\WINDOWS\system32\pmls64.dll was not found. Reinstalling the program may fix this problem." I've tried completely deleting Firefox and reinstalling and it opens a new tab, but when I close it i get the same error message.

I'm trying to install Firefox on my work computer (ARM64 version), but when I do I'm getting the crash report window at the end of the installation process (multiple times in a row), if I try to open the browser (only once), and during the uninstallation process (also multiple times in a row). I've tried a clean reinstall multiple times, including deleting the folders from program files, %APPDATA%, and all registry entries I could find (HKEY_CURRENT_USER>>SOFTWARE, HKEY_LOCAL_MACHINE>>SOFTWARE, HKEY_LOCAL_MACHINE>>SOFTWARE>>WOW6432Node).

I've contacted IT and they don't seem to think anything pre-installed should be affecting this. I'm unable to get a crash ID as I'm unable to even start the browser - all I get is the Firefox crash reporter, immediately. Is someone able to help me figure out why I can't get this working?

Firefox won't open. System says it can't find VCRUNTIME140.DLL. There are SEVERAL copies on the drive. I believe I Refreshed and Reinstalled? And still cannot run.

This is the first time Firefox has failed in years. There are no instructions for this specific problem. FWIW I just installed AURA seemingly without problems.

Richard PS - Wouldn't it be great if the library of proven volunteer responses was searchable? r

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

- Had 3 windows open with numerous tabs and tab groups - Firefox sync was enabled, as well as a 2-3 plugins AFAIK - Version installed is latest as of this writing 139.0.4 - Initial crash caused by opening and quickly closing (IF that succeeded before crash) a onedrive share link - Cannot start firefox any more, also not in safe mode - the only thing that works is launching it with a fresh profile.

The report ID is bp-a8c824fc-a7fb-4290-a72b-b63160250620

Ideally I can resolve this without needing to refresh or start over with a new profile

Firefox was working perfectly up until this morning and I'm pretty sure there wasn't a new update today. But now when I open the app a new window will briefly pop up for a fraction of a second and then disappear. Unfortunately this prevents me from accessing troubleshoot mode or crash reports so i can't provide much information on specifics.

I followed the steps here: https://support.mozilla.org/en-US/kb/firefox-keeps-crashing-startup and they haven't worked so far. I tried a clean install and restarting my computer multiple times, but no dice. There also don't seem to be any compatibility issues with the most recent version in the release notes.

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.

Ive uninstalled it multiple times, done just about everything suggested online, and even got it working for a bit off the Microsoft store. But for some reason, my desktop Firefox will not open at all.