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Fix Windows Update 404 Not Found Error: Practical Steps - How to Fix Defender Failed to Start Error-How to Enable PowerShell at System Startup

Updated 2026-06-15 08:57:13developer-tools
Fix Windows Update 404 Not Found Error: Practical Steps - How to Fix Defender Failed to Start Error-How to Enable PowerShell at System Startup
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.