Directory sync errors: duplicate attributes

Overview

Duplicate proxyAddresses or UPNs block object sync—users vanish from cloud groups.

Detection

Sync error reports in Entra + event logs on sync server.

Resolution pattern

1. Identify winning on-prem object vs orphan cloud-only user.
2. Clean attributes in AD; force delta sync.
3. If merge needed, export before state snapshot.

Prevention

Provisioning standards forbidding manual cloud mailboxes mirroring synced users.

SLA

Treat Sev2—impacts MFA licensing and dynamic groups within hours.