Fix Windows Defender Sync Issues with Microsoft 365 - Step-by-Step Checklist for Defender Update Errors-Fix Windows Defender Firewall Blocking an App

Updated 2026-06-13 20:20:16browser-issues
Fix Windows Defender Sync Issues with Microsoft 365 - Step-by-Step Checklist for Defender Update Errors-Fix Windows Defender Firewall Blocking an App
Before changing system settings, save your work and note the exact error text so you can compare results after each step.

Extra verification checklist

  • Restart the affected app after changing permissions or configuration files.
  • Test the same workflow in a clean browser profile or a temporary user account.
  • Compare the result on another network if the error may be connection related.