Some problems occur when your Internet security program was set to trust the previous version of Firefox, but no longer recognizes your updated version as trusted. Now how to fix the problem: To allow Firefox to connect to the Internet again;

• Make sure your Internet security software is up-to-date (i.e. you are running the latest version).
• Remove Firefox from your program's list of trusted or recognized programs. For detailed instructions, see

Configure firewalls so that Firefox can access the Internet. {web link}

I tried the firewall thing, but it didn't work. I reinstalled windows a third time, but this time I disconnected internet and made a local account. First thing in windows, I installed Firefox, and it worked. No problems, So I installed all the drivers. When it was all done, I tested firefox. Still worked. So after restarting, I connected to my nephews Microsoft account, After doing that, it syncs something to the computer that broke firefox. So, I'm back to firefox flashing and closing. I tried the firewall thing again, but it does nothing.

Obviosuly a solution for me is to reinstall the computer a fourth time and not sync the old settings. But I would like it if we could try to find out what is breaking firefox so that this won't happen again if he ever need to reinstall windows again.

Were you talking about Firefox sync or something else?

If Firefox, try this;

You can use sync to share passwords, bookmarks, and history. Anything else may not be compatible between different browser versions or computer systems.

I tried the firewall thing, but it didn't work.

Hello! How about this one?: How to let Firefox use the internet on your Windows computer

To be clear, Firefox worked with a local windows account. But when I signed in to the Microsoft account. Windows synced old settings that breaks Firefox so it won't open. Nothing works, It just flashes and closes. I have tried everything I could find online. Like I said in my first post. " I have tried re-installing Firefox, deleted all Mozilla and Firefox files and folders and clean installed Firefox. Troubleshoot mode don't work, it just flashes and closes too. I checked for Crash Reports, but there are none." There is some setting in windows that is breaking Firefox.

t_lsv said

I tried the firewall thing, but it didn't work.

Hello! How about this one?: How to let Firefox use the internet on your Windows computer

Don't work. I just tried this very thing. I even tried deleting firefox, not only uninstall but all files, folders and used regedit to get rid of every Mozilla entry. Restarted computer, reinstalled firefox, Still don't work. Just blinks and closes.

Update: I installed Opera and Chrome to see if those browsers work, and they do the same thing. Blinks and closes. So this isn't a Firefox only problem.

. . . But when I signed in to the Microsoft account . . .

As Microsoft settings are causing the problem, You should also try asking here: https://support.microsoft.com

http://answers.microsoft.com/en-US/windows/forum/windows_10

Or you can delete the synced data and start over.

t_lsv said

. . . But when I signed in to the Microsoft account . . .

As Microsoft settings are causing the problem, You should also try asking here: https://support.microsoft.com

http://answers.microsoft.com/en-US/windows/forum/windows_10

Or you can delete the synced data and start over.

I just reinstalled the computer again with a local account, and found how to delete the synced data. Tested Firefox and it does work again. Once it's done updating, I thought of creating a recovery point, in case there is a problem. Hopefully I can just go back to that point and get rid of the problem. The synced data is deleted so there shouldn't be any problems. Anyway, thank you both or your help.

Glad to help. Safe Surfing.

Note that such issues can be caused by a corrupted or incomplete Visual C++ installation that is missing runtime components (Redistributable Packages) required by Firefox, especially VCRUNTIME140_1.dll.

See "Visual Studio 2015, 2017, 2019, and 2022":

• https://docs.microsoft.com/en-US/cpp/windows/latest-supported-vc-redist
• https://aka.ms/vs/17/release/vc_redist.x64.exe
• https://aka.ms/vs/17/release/vc_redist.x86.exe

You may also have to install the Visual Studio 2013 Redistributable Package. You need to reboot the computer.