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Windows Defender Not Opening on Windows 11: How to Fix - Cloudflare Error 521: Web Server Down Troubleshooting Guide-Bypass PowerShell Execution Policy for One Script

Updated 2026-06-13 13:10:39developer-tools
Windows Defender Not Opening on Windows 11: How to Fix - Cloudflare Error 521: Web Server Down Troubleshooting Guide-Bypass PowerShell Execution Policy for One Script
Likely symptom
Likely cause
Safe rollback

Verification route

  • Repeat the original action, not only a simplified test case.
  • Restart the app or reload the service after configuration changes.