Back to All Scenarios
PASSEDcloud / azure_ad_sync_failure
Azure AD Sync Failure — Users Can't Authenticate
Azure AD Connect sync fails due to an expired service account password. Password hash sync stops working. New users created in on-prem AD are not provisioned in Azure AD. Existing cloud users with changed passwords cannot authenticate to M365 services.
Pattern
AZURE_CLOUD
Severity
CRITICAL
Confidence
85%
Remediation
Remote Hands
Test Results
| Metric | Expected | Actual | Result |
|---|---|---|---|
| Pattern Recognition | AZURE_CLOUD | AZURE_CLOUD | |
| Severity Assessment | CRITICAL | CRITICAL | |
| Incident Correlation | Yes | 23 linked | |
| Cascade Escalation | N/A | No | |
| Remediation | — | Remote Hands — Corax contacts on-site support via call, email, or API |
Scenario Conditions
Azure AD Connect v2.x. Password hash sync enabled. Service account password expired 6 hours ago. 2000 synced users. 50 users changed passwords since sync failure. M365 E3 licenses.
Injected Error Messages (2)
Azure AD Connect sync failure — Export to Azure AD failed with error 'stopped-server-down', service account credentials expired, Event ID 6100: password hash sync heartbeat stopped, last successful sync: 6 hours ago, 2000 directory objects out of sync
M365 authentication failures for synced users — users who changed on-prem passwords cannot sign in to Teams/Outlook/SharePoint, Azure AD password hash stale, MFA prompts failing for 50+ users, Conditional Access policies blocking due to risk detection
Neural Engine Root Cause Analysis
The Azure AD Connect service has failed due to expired service account credentials, preventing synchronization between on-premises Active Directory and Azure AD. The 'stopped-server-down' error combined with password hash sync heartbeat failure and 2000 out-of-sync objects indicates authentication failure rather than network connectivity issues. This is a common operational issue that occurs when the service account used by AAD Connect reaches its password expiration period.
Remediation Plan
1. Verify service account credentials have expired in Azure AD portal 2. Reset/renew the service account password in Azure AD 3. Update AAD Connect configuration with new credentials using the AAD Connect wizard 4. Restart Azure AD Connect sync service 5. Force a manual sync cycle to clear the backlog 6. Monitor sync status and verify 2000 pending objects are processed 7. Implement credential expiration monitoring to prevent future occurrences
Tested: 2026-03-30Monitors: 2 | Incidents: 2Test ID: cmncjk76i0259obqewzfreo5z