I’ve recently encountered an issue on Windows 11 devices whereby Windows Defender and the Security portal refuse to open, with it showing a “You’ll need a new app to open this windowsdefender link” popup. This appears to stem from a corrupt app install after one of the recent patches.

The Solution
The solution requires that PowerShell be ran as an administrator. Run the following commands one at a time and test access to Defender / the Security portal after each command.
Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage # Attempt to fix the Security Health UI App
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”} # Disable development mode of all Apps which should resolve the issue







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