"You'll need a new app to open this windowsdefender link" fix

Thank you @TrippCollins - worked for me!

(My Defender went haywire after Windows 11 Upgrade from Windows 10).

To add on, I am having this issue and rest my Windows 11 completely with it still not resolved. I am using an insider build. Could this be why?

First, I want to say thank you for this info as it worked and Microsoft defender is now active and working again working. But while the what to do is accurate, the how to do it may not be clear to those of us who are not computer geeks. Luckily for me my son is a computer geek in the navy and was able to help. This is the how. To get to the power shell, go to magnifying glass Icon on your bottom taskbar and type in 'windows power shell', and click on it. It will open a small black screen. It may also open a full website screen (just close the website screen and you should have the small black screen that says Window power shell. There will be a small flashing white cursor. At the flashing cursor, either copy and paste the first instruction, Set-ExecutionPolicy Unrestricted for type it in, then hit enter. You will get screen with a message about execution policy change, with 4 options at the bottom A. Yes B. Yes to All C. No D. No to All. At the flashing cursor type in the letter B (for yes to all) and then hit enter. At the next screen copy and paste, Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"} and hit enter. A screen will appear with a blue section running program update for couple of minutes. When complete you will need to enter the 4th step of, Set-ExecutionPolicy restricted and hit enter. Agiain you will get the A, B, C, and D options. Clicking on the desired option won't do anything, you will need to enter the option letter B (yes to all at the white cursor. Hit enter and you should be all set. After complete, restart your computer and go to your windows defender and you should find it active again and working fine.

The 4-step process works, but some of us retired folks are not fully up on how to execute the process. Hope this helps some not quite as savvy as computer geeks.

Impressive how broken win11 is really, even fedora is easier to use as a daily driver at this point.

Also this fix doesn't work for me.

For Windows 11, this worked for me.

Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage