After yesterday’s FF 142 update, the browser refuses to open. It shows up in the task bar, but doesn’t fill the screen. Win 10 Pro, fully patched, Norton 360/Lifelock totally up to date, etc. 6 core AMD processor, 32 G RAM. FF worked well until the latest update.
Edge runs, Chrome runs, just not FF. No Norton security settings were changed… Kind of a pain. Among the suggested ‘fixes’, R&R Firefox, R&R Norton 360…Did the FF one, but R&R Norton seems bit extreme. Anyone?
@ddunk1946 Does anything show in your Norton history or Firewall that suggests Norton is blocking FF ? If not. Check the settings below in your Norton install. One of them may be able to clear things for you. Make sure you restart the computer to allow the changes to be made in Norton.
SA
Additionally, I found AI information that MAY also be of assistance:
AI Overview
If Firefox isn’t opening after the 142 update, there are several troubleshooting steps you can try. Here’s a breakdown of common solutions:
1. Restart your computer
A simple restart often resolves temporary glitches that might prevent applications from launching.
2. Check for conflicting software
Security software: Antivirus, firewall, or parental control software (like Microsoft Family Safety, which has been known to interfere with browser launches) could be blocking Firefox from running. Try updating your security software to the latest version, temporarily disabling it, or removing Firefox from its trusted applications list to see if that resolves the problem.
Other programs: Ensure no previous Firefox processes or other programs are interfering with the new update by restarting your computer.
Visual C++ Redistributable: If you recently uninstalled an application that used Visual C++ runtime components, a corrupted or incomplete installation could be causing issues. Download and run the latest installer for Visual Studio from Microsoft’s website and then reboot your computer.
3. Restart Firefox in troubleshoot mode
This mode disables extensions, uses the default theme, and turns off hardware acceleration, helping identify if any of these are the cause of the issue.
On Windows, press and hold the Shift key while opening Firefox.
On Mac, hold down the Option key while starting Firefox.
On Linux, open a terminal and run
firefox -safe-mode.4. Clear startup cache
If the startup cache (used to speed up launch) is corrupted, Firefox might fail to open. Clearing it might resolve the issue.
Completely close Firefox.
Open the Run box (Windows key + R) and type
%localappdata%\Mozilla\Firefox\Profiles\and click OK.Locate the folder named
startupCachewithin your profile folder.Delete all files inside the
startupCachefolder.Re-open Firefox.
5. Reinstall Firefox
Reinstalling Firefox ensures all program files are correctly installed without typically removing your profile data. Download the latest version from the official Mozilla website, uninstall the current version, manually delete the program folder if necessary, and then reinstall Firefox.
6. Refresh Firefox
Refreshing Firefox can restore it to its default state while saving important information like bookmarks. To do this, open Firefox, go to Help > More Troubleshooting Information, and click “Refresh Firefox…”.
7. Create a new Firefox profile
Creating a new profile can help determine if a corrupted existing profile is causing the problem. To create a new profile, close Firefox, open the Run box (Windows key + R), type
firefox.exe -P, and follow the prompts in the Profile Manager.If these steps don’t resolve the issue, consider seeking further assistance on the Mozilla Support forum.
SA
Thank you! I have done most of that. I’ve been in high-technology/computers since the late 70s, but none of that is helping me these days. 
Will try those extra steps tomorrow. Will report back. As I said, my system was fine until the FF 142. Sigh. Be well and thanks again! DD
You’re most welcome!! Please post-back what your findings are, there must be others who have or are seeing this and haven’t posted yet.
SA
Well, this is embarrassing. As I said, I operated two sticks and bricks computer stores in the 80s and have run into my share of unwilling/lazy (I’ll stop there…) end users. I have always looked for the answer on my own before I contacted official help channels/communities. Google is your friend, although I think that might be AI is your friend these days. But, seriously, all I had to do is refresh FF, shift key, etc. and I was back in business. I swear that I did that yesterday but didn’t get the ‘refresh Firefox’ popup. Sigh. Anyway, I am good and have saved all the excellent information you and the community have provided. Much appreciated!!!
I know the feeling also. Lots of knowledge about Cobol, CICS, PL1 and IBM 370 for me that does not translate into todays language.
Sometimes I look back on those dumb users for yesteryear and realize those dumb users are now me.
hahaha My point, exactly! My motto these days is, ‘don’t let yourself get old!’ Be well and thanks! My ‘big box’ experience was DEC PDP 11/34a’s w/RM02 platter drives. How times have changed.
