Hi pattyfingers, that sounds like quite an ordeal.

Did you already try the "full" or "offline" installer in case your firewall (or something else) is blocking the "stub" or "online" installer? Those are available from the following page:

https://www.mozilla.org/firefox/all/

Yes- I'm only using the offline installer, and shutting off firewall and disabling antivirus software on installing. Is there an install log created somewhere that might give me a clue?

Hi pattyfingers, the installer creates a log in the program folder. Anything useful? Either:

• C:\Program Files\Mozilla Firefox => install.log
• C:\Program Files (x86)\Mozilla Firefox => install.log

Your original post mentioned some processes in memory. So perhaps Firefox is installing correctly but cannot launch fully. In that case, I suspect Firefox wouldn't log anything useful, but the Windows event log might show some kind of application event.

Try to start Firefox in Safe Mode to see if that works.

• Windows: hold down the Shift key while starting Firefox
• Mac: hold down the Options key while starting Firefox

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Maybe also check the Windows Event log.

I appreciate the feedback! BTW, I am working with the 64 bit offline installer, and have removed my old profile so the installer will create a new one. The install log is unremarkable, showing no errors. Event Viewer shows entries for an application hang for Firefox at the time it froze during the update. These are followed by several WMI errors, likely created upon each attempt to reinstall that reads: Event filter with query "SELECT * FROM __InstanceModificationEvent WITHIN 60 WHERE TargetInstance ISA "Win32_Processor" AND TargetInstance.LoadPercentage > 99" could not be reactivated in namespace "//./root/CIMV2" because of error 0x80041003. Events cannot be delivered through this filter until the problem is corrected. I cannot start Firefox in Safe Mode, as it will not start at all. Each attempt to launch it after the installation does nothing more than place a running instance of firefox.exe in Task Manager that cannot be ended except by rebooting. I did happen to notice another similar post within a few minutes of my original from user SD Robot at https://support.mozilla.org/en-US/questions/1264440#sign-out The only thing I have not tried that he has is running the 32 bit installer. I have little confidence that would bring different results. Thanks again for any suggestions!

Hi pattyfingers, one of the changes in Firefox 68 is a new launcher process. Perhaps it would be worth trying to disable that feature. Since you can't load any tabs, this would have to be done through a file in your profile folder. I haven't tested this, but here is the idea:

(1) Open your profile folder

You can type or paste

%APPDATA%\Mozilla\Firefox\Profiles

in the Windows 7 Start menu Search box and press Enter to launch a new Windows Explorer window in this hidden folder:

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

Now double-click into your currently active profile folder.

(2) Set Windows to show all file extensions

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

(3) Add a new line to the prefs.js file

Right-click prefs.js and click Edit (or Open With) to open the file in Notepad (or other plain text editor).

Search in the file for a line similar to:

user_pref("browser.launcherProcess.enabled", true);

If you find that, change true to false:

user_pref("browser.launcherProcess.enabled", false);

Otherwise, paste that line at the bottom of the file.

Save and close.

Any difference?

There are other optional configuration files that can force that setting. I don't know whether that is required to test this theory.

Adding that line made no difference (the line did not exist, likely since Firefox has never started so it hasn't had a chance to even access the newly created profile). Firefox still does not start at all and requires a reboot to clear the process from Task Manager. I checked my old profile (updated when the Firefox update was attempted) and the line does exist, set to false.

Hi pattyfingers, thank you for checking that.

Is there anything special about how you start Firefox? For example, using Run as Administrator, setting Environment variables, or running Firefox inside a sandboxing program?

Just a simple double click on the desktop icon or single click the tray icon. I did try Run as Administrator once, but there was no difference. Haven't tried a sandbox, and am unsure how to.

Still no successful installation, and I don't have the luxury of System Restore as my C partition is installed on a SSD. Is there a Firefox uninstaller that will completely remove all traces?

Hi pattyfingers, I'm not aware of an uninstaller that will remove all traces. Do you want to back up your profile folder data first?

You mentioned a C drive, which implies that your Firefox or Firefox data might be installed on a different drive??

I wonder whether it would make sense to reinstall Firefox 67.0.4 for the time being. I will send you a link in a private message.

See also https://support.mozilla.org/en-US/kb/install-older-version-of-firefox#firefox:win7:fx68

Thanks to everyone for your feedback, however even the 67.0.4 installer does the same thing as 68.0 and Firefox will not start after installation. I installed in Safe Mode to be sure there were no conflicts with AVG or Zone Alarm and long ago removed my profile to a flash drive so Firefox is forced to create a new one. As before, each time I attempt to start Firefox it still creates an instance in Task Manager that cannot be closed except by a reboot. I was hopeful by another post that AVG was the issue, but have two other computers running similar setups that updated to v.68.0 with no issues. Not sure where to turn next but will keep exploring options as I have time and will repost if I find a solution.

You mentioned ZoneAlarm.

This article may be outdated but see Firefox won't start - find solutions under the No error message section:

Firefox will not start after updating

If you use certain versions of ZoneAlarm or other Internet security software that includes a "Virtual Browsing" feature, it can prevent Firefox from starting. Check virtualization settings and clear the virtual cache, if your Internet security software includes this feature, or visit the software provider's support site for more help.

I searched for recent info and found this, posted Apr 7, 2019:

https://forums.tomshardware.com/threads/since-i-installed-zonealarm-firefox-has-serious-problems.3468506/

The suggestion was to uninstall ZoneAlarm and use a different firewall (or the Windows firewall).

After a lengthy uninstall of AVG this problem is mostly solved. I was finally able to reinstall Firefox 68.0, however interestingly upon first launch (which I was relieved finally happened) it prompted my for a Refresh. I'm not sure how that got triggered since all previous profile folders and directories had been removed prior to the install. I've been able to restore my old profile and it's working well, but when Firefox is closed there is still an instance of firefox.exe in Task Manager that can't be shut down by End Process. Is this part of the new version, that it runs resident or do I still have a bug to work out? BTW, I left Zone Alarm as is and there doesn't seem to be any conflict with Firefox. Ironically I have 2 other computers running similar security software (AVG, Zone Alarm) that both updated to v.68.0 with no issues, so I'm not sure why this one choked. It's certainly nice to have my browser back though. Thanks to everyone who weighed in on this issue!

Thanks for the follow-up. I'll mark this question solved based on your reply that uninstalling AVG allowed you to reinstall Firefox 68.

As for the remaining firefox.exe process when Firefox is closed that cannot be ended in Task Manager, let us know if you figure that one out! Since ZoneAlarm has been known to cause Firefox issues, you might want to consider uninstalling it temporarily and turn on the Windows firewall, to see if that resolves the issue.

The firefox will not start. Cannot end process... thread you mentioned before has a link to this AVG forum thread: https://support.avg.com/answers?id=9060N0000005M4Z You or others who had to uninstall AVG to get Firefox to work may want to follow it, in case there's a solution that allows you to reinstall AVG.

If you want to install another AV product, Microsoft Security Essentials is a good permanent antivirus for Windows 7. Windows 8/10 has Windows Defender antivirus protection built-in.

pattyfingers said

when Firefox is closed there is still an instance of firefox.exe in Task Manager that can't be shut down by End Process. Is this part of the new version, that it runs resident or do I still have a bug to work out?

Forgot to answer. When I close Firefox 68.0 64-bit on my Windows 7 computer, there is NO remaining firefox.exe process in Task Manager (I'm using Microsoft Security Essentials with the Windows Firewall). If you see one, it's not normal.

Thanks Alice. I've reverted to the same setup (Windows Defender, Firewall). In monitoring the stray firefox.exe process I see that it disappears about 10 minutes after Firefox is closed. Not perfect, but quite acceptable considering all the brain damage this problem caused!

pattyfingers said

Thanks Alice. I've reverted to the same setup (Windows Defender, Firewall). In monitoring the stray firefox.exe process I see that it disappears about 10 minutes after Firefox is closed. Not perfect, but quite acceptable considering all the brain damage this problem caused!

You're welcome. Just checking - what Windows version are you on? On Windows 7, Windows Defender only protects against certain malware (spyware); antivirus protection wasn't added until Windows 8 (ref.). Windows 7 users need to download Microsoft Security Essentials. When MSE is installed, it disables Windows Defender (ref).