VDDK Error 3 Troubleshooting

A Backup or Replication job fails with an error containing 'VDDK error: 3'

This most often occurs when forcing a VMware Backup Proxy to use 'Virtual Appliance' mode and deselcting the 'Failover to network mode.'

There are four situations that commonly cause this error:

1. The VM acting as VMware Backup Proxy is on a different ESXi host than the source VM, and the source VM was added to the job through the host directly (as opposed to through the VC).
2. The datastore containing the disks of the source VM are not accessible by the ESXi on which the VM acting as VMware Backup Proxy is running.
3. The VM acting as VMware Backup Proxy and the source VM are managed by different VC's.
4. The VM acting as VMware Backup Proxy and the source VM are managed by the same VC, but located in different DataCenters

In the first case above, add the affected VM to the job by the vCenter.

In the other situations,  Virtual Appliance (HOTADD) mode is not applicable or possible given the current VMWare architecture.

Review:

• Requirements for the Virtual Appliance mode
• Appliance Mode (Hotadd) Requirements and Troubleshooting