Fix PowerShell Service Unavailable on Windows 11 - Windows Defender Not Showing in Settings After Update-How to Resolve Defender 404 Error

Updated 2026-06-18 20:21:46security-tools
Fix PowerShell Service Unavailable on Windows 11 - Windows Defender Not Showing in Settings After Update-How to Resolve Defender 404 Error
Before changing system settings, save your work and note the exact error text so you can compare results after each step.

Extra verification checklist

  • Restart the affected app after changing permissions or configuration files.
  • Test the same workflow in a clean browser profile or a temporary user account.
  • Compare the result on another network if the error may be connection related.