How to Fix OneDrive Sync 504 Gateway Timeout Error - Fix ERR_TUNNEL_CONNECTION_FAILED in Chrome on Mac-Windows Terminal Permission Denied: Troubleshooting Checklist

Updated 2026-06-14 00:15:45windows-fixes
How to Fix OneDrive Sync 504 Gateway Timeout Error - Fix ERR_TUNNEL_CONNECTION_FAILED in Chrome on Mac-Windows Terminal Permission Denied: Troubleshooting Checklist
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.