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.