More detail please. Let me see what version I have of Win 11. I'm updating now.

Your User Agent shows: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Firefox/91.0

Please verify Windows 11

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 have no issue. see screenshot

-my system is Windows 11 Pro , version 21H2 and build; 22000.120 - after deinstallation of the Windows 11 update FireFox started , so Bitdefender is not the problem.

You should also ask your question here; https://support.microsoft.com

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

Type about:support in the address bar and press Enter. Under the main banner, press the button; Copy Text To Clipboard.. Now in the Reply Box on the forum page, do a right-click in the box and select Paste.

If the data is too big, do not worry. It's the top part we need to look at.

This will show us your system details. No Personal Information Is Collected.

How about testing in safe mode.

I too am unable to get firefox to work. I get a blank screen. I tried to uninstall and then reinstall firefox but now am getting an error with missing DLL?

We have seen this a lot of late.

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

Install both 32-bit and 64-bit "Visual Studio 2015, 2017 and 2019" downloads, (x86: vc_redist.x86.exe and x64: vc_redist.x64.exe) from https://support.microsoft.com/help/2977003/the-latest-supported-visual-c-downloads

You may not need the latter (32-bit version) if you use 64-bit Firefox. You may have to reboot the computer. ++++++++++++++++++++++++++++++++++++++++++++++ In another thread, a user reported that a recent update of Malwarebytes Anti-Exploit (version 415) may be causing symptoms similar to the VC Runtime problem. If you have MBAE, it should have a setting to exempt Firefox. You could test whether that makes any difference.

I had this problem also. Turned out the problems was solved by turning off Norton 360 VPN. When Firefox was open I turned on the Norton 360 VPN and Firefox now works correctly. Lesson learned is to check security software and restart computer.