Storm season is back, bringing with it the potential for significant weather events. If you have clients in areas prone to infrastructure disruption, visit the Disaster Recovery Resources guide for preparedness information. Datto recommends performing proactive disaster recovery testing to mitigate potential downtime. See our articles about the importance of disaster recovery testing and Preparing For A Cloud Virtualization Test: Policies, Procedures, And Partner Responsibilities to learn more. For live updates, follow @datto on Twitter.

Critical Backup Failure: Error Reading from Source File '/Home/Agents/#-TestDataset/Vddk-Fuse/VMDKname.Vmdk'



When attempting to backup a virtual machine under the agentless backup solution, you receive the error Critical backup failure: Error reading from source file '/home/agents/#-TestDataset/vddk-fuse/VMDKname.vmdk'. Expected bytes (value), actual bytes 0.


  • Datto SIRIS
  • Agentless Backups (VMWare)


  • Snapshots on the hypervisor require consolidation.
  • Changed Block Tracking (CBT) requires resetting.
  • The Datto appliance is full.
  • The live dataset on the Datto appliance is corrupt or unusable.


Attempt a backup after following each step:

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