Hi jace, welcome in community
To resolve this, open an elevated PowerShell window and run
Get-AppxPackage Microsoft.SecHealthUI -AllUsers | Reset-AppxPackage
To reset the app. If that command throws an error, which occasionally happens depending on your specific Windows build, you can force the re-registration by executing
& {$manifest = (Get-AppxPackage *Microsoft.SecHealthUI*).InstallLocation + '\AppxManifest.xml' ; Add-AppxPackage -DisableDevelopmentMode -Register $manifest}
instead. If the PowerShell commands do not work, or if the app opens to a completely blank screen, the core executable is likely broken. To apply a more thorough fix, open File Explorer and navigate to
C:\Windows\System32\SecurityHealth.
Inside this directory, look for a folder named with a version number and open it to find SecurityHealthSetup.exe. Right-click this file and choose to run it as an administrator. The setup will execute silently in the background, so wait about a minute before attempting to launch Windows Security again. Keep in mind that if the directory is entirely empty, you will need to copy that setup executable from a healthy machine running the same Windows build.
Let me know
Elvis