Solved: Botched Domain Migration in Jan 2024 – Just Discovered the Damage. How Do I Fix This?

🚀 Executive Summary TL;DR: A botched domain migration often leads to ‘Access Denied’ errors because applications store user permissions by old, orphaned Active Directory Security Identifiers (SIDs). The fix involves diagnosing new SIDs and updating application databases, with Active Directory Migration Tool (ADMT) and sIDHistory migration being the crucial preventative measure. 🎯 Key Takeaways Domain migrations can cripple applications by creating ‘orphaned’ user accounts, where application databases still reference old Active Directory Security Identifiers (SIDs) instead of new ones. The Active Directory Migration Tool (ADMT) is critical for domain migrations, specifically its feature to migrate sIDHistory , which stamps a user’s old SID onto their new account, ensuring applications recognize them. Solutions for SID mismatch issues range from emergency manual SQL updates for critical users, to scalable PowerShell scripts for bulk database remediation, or a ‘Nuke and Pave’ strategy inv