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Fix 'Windows Security Cannot Connect to Microsoft Defender' Error - Resolve Error 0x80070643 in Windows Update-Outlook 404 Not Found: Quick Fixes for Microsoft 365

2026-06-13 22:33:34
Fix 'Windows Security Cannot Connect to Microsoft Defender' Error - Resolve Error 0x80070643 in Windows Update-Outlook 404 Not Found: Quick Fixes for Microsoft 365

Result check

  • Keep one change per test run so you know which step helped.
  • Undo temporary changes after the issue is confirmed.