SIRIS, ALTO, and NAS: Datto Windows Agent: Error: "Snapshot State: 5 Error Status: 0x0000001b"



When you start a backup using the Datto Windows Agent, you see a generic "Critical backup failure during data transfer" error in the device GUI. In the agent logs, you see "Snapshot State: 5 Error Status: 0x0000001b."


  • Datto Windows Agent


You have deduplication enabled on one or more volumes included in the backup. You'll see the following error in the Agent Logs from the Protect tab:

Snapshot State: 5 Error Status: 0x0000001b Message: RetrieveControlRegionExtents failed with status (0xc000000d) during PerformSnapshot_Phase2


Disable deduplication or exclude any deduplicated volumes from backups. 

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