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Fix Windows Update Connection Refused on Windows 11 - Windows Defender 404 Error in Command Prompt Fix-How to Resolve Windows Defender Update Authentication Failure

2026-06-13 13:42:13windows-fixes
Fix Windows Update Connection Refused on Windows 11 - Windows Defender 404 Error in Command Prompt Fix-How to Resolve Windows Defender Update Authentication Failure

Final checklist

  • Confirm that the same symptom is gone after a restart or refresh.
  • Keep the smallest working change and undo temporary diagnostic settings.