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Troubleshoot a Legacy DirSync or Microsoft Entra Connect Sync Service

Troubleshoot a Legacy DirSync or Microsoft Entra Connect Sync Service

“DirSync” is an older name commonly used for Microsoft’s directory synchronisation tooling. In a current environment, first identify the actual product installed: Microsoft Entra Connect Sync, Microsoft Entra Cloud Sync, or a legacy unsupported component.

Start with service health

  1. Open Services on the sync server and identify the Microsoft Entra/Azure AD sync service.
  2. Check whether the service is running and review the Windows Application event log around the failure time.
  3. Confirm the server can resolve DNS and reach required Microsoft endpoints over HTTPS.
  4. Check whether the service account, connector credentials or certificate recently changed or expired.

Use the product tools

For Entra Connect Sync, use the Synchronization Service Manager and the supported PowerShell module to inspect connector/run history. A failed import, sync or export step usually gives a more useful error than repeatedly restarting the Windows service.

Do not keep an old synchronisation product running simply because it still starts. Verify the installed version is supported and plan an upgrade or migration when the server is outside Microsoft’s supported lifecycle.