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

for windows 11 users:

try this command :

Add-AppxPackage -Register -DisableDevelopmentMode "C:\program files\windowsapps\Microsoft.SecHealthUI_1000.22621.1.0_x64__8wekyb3d8bbwe\appxmanifest.xml"

This did work on my Windows 10. Just ignore the errors that you may get.

Hi this post is to help people with windows 10 and 11 windows security not working

On windows 11 do this

1. launch powershell as an admin
2. Set-ExecutionPolicy Unrestricted
3. Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
4. Set-ExecutionPolicy restricted

IGNORE THE ERRORS

on windows 10 do this

1. launch powershell as an admin}
2. run get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage
3. if it doesn't work do this
   4) run Add-AppxPackage -Register -DisableDevelopmentMode "C:\Windows\SystemApps\Microsoft.Windows.SecHealthUI_cw5n1h2txyewy\AppXManifest.xml"
4. run get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage

The Windows 11 fix worked for me, but ONLY when run by the user account that had the problem and first assigning that account to the Administrators group (and subsequently downgrading it back to Users). Other combinations ran (e.g. run by Administrator or by user before assigning as administrator) but failed to correct the problem.

I was facing the same exact issue.It was working for Admin account but I was unable to launch it for secondary (Standard User) accounts. The solution described in OP did not work for me. I removed secondary account and then added it back and it worked for me.

Thank You so much! It worked. ^_^