MongoDB Authentication Failed Error 18: Causes and Fixes - Resolve Windows Defender Port Allocation Error-Create Self-Signed SSL Certificate on Windows 11

Updated 2026-06-13 18:38:56database-tools
MongoDB Authentication Failed Error 18: Causes and Fixes - Resolve Windows Defender Port Allocation Error-Create Self-Signed SSL Certificate on Windows 11
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.