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



This article describes how to troubleshoot the error Critical backup failure: Error reading from source file '/home/agents/#-TestDataset/vddk-fuse/VMDKname.vmdk'. Expected bytes (value), actual bytes 0.


  • On the hypervisor, verify that there are no snapshots in need of consolidation for the VM in question. If there are snapshots needing removal, consolidate them.

  • On the Datto appliance, delete the live dataset for the VM, then perform a new backup. If the backup fails with the same error, continue to the next step.

  • Recheck for snapshots in need of consolidation, as kicking off a new backup could hang another snapshot. If needed, consolidate the snapshots.

  • Verify that you can successfully take a manual quiescing snapshot, then perform one final consolidation if needed and reset Changed Block Tracking (CBT) on the VM using the following documentation:
    Resetting Changed Block Tracking for VMware vSphere virtual machines (external link)

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