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Home / developer-tools / How to Fix Windows Defender Error 504: Step-by-Step Guide - Windows 10: Port Already Allocated Error in Windows Defender Fix-Troubleshoot Error 0x80070020 Port Allocation

How to Fix Windows Defender Error 504: Step-by-Step Guide - Windows 10: Port Already Allocated Error in Windows Defender Fix-Troubleshoot Error 0x80070020 Port Allocation

Updated 2026-06-13 15:26:56developer-tools
How to Fix Windows Defender Error 504: Step-by-Step Guide - Windows 10: Port Already Allocated Error in Windows Defender Fix-Troubleshoot Error 0x80070020 Port Allocation
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.