Fix OneDrive Sync Error 0x8004de40 – Authentication Failure - Windows Defender Can't Connect? Try These Fixes-Chrome Backup Restore Failed Error Code: Fixes

Updated 2026-06-14 04:59:14macos-help

Fix OneDrive Sync Error 0x8004de40 – Authentication Failure - Windows Defender Can't Connect? Try These Fixes-Chrome Backup Restore Failed Error Code: Fixes

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.