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)