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Windows Security App Not Working After Update: Fixes - Windows 11 Defender Real-Time Protection Won't Stay On-Nginx Upstream Connection Refused: Diagnosis and Fixes

Updated 2026-07-28 17:07:29developer-tools
Windows Security App Not Working After Update: Fixes - Windows 11 Defender Real-Time Protection Won't Stay On-Nginx Upstream Connection Refused: Diagnosis and Fixes
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.