Plugin for VMware 11.3 and upper Fails to Open Virtual Disk for VM due VDDK error Code 14009 (4039199)

Backup for VM fails with error:

Failed to open virtual disk  and [14009] The server refused connection

We see the same error when we run Diagnose Virtual Machine from Actions in the selection tree.

Also Debugging traces point to the same error:

There is no connectivity between the ESXi host and the VMware proxy.

This issue also occurs in situations where vCenter and some of the hosts are running VMware 5.5 or upper but the host where is located the VM is running VMware 5.1 or below.

NetVault Backup Plug-in for VMware 11.3 and upper is not compatible with VMware 5.1 and below.

NetVault Backup Current Version - Compatibility Guide

Check the connectivity:

1. On PowerShell, run the following commands. Repeat if there are multiple ESXi
   • Test-NetConnection -ComputerName "ESXihostname" -Port 902
   • Test-NetConnection -ComputerName "ESXihostname" -Port 443
   • Test-NetConnection -ComputerName "vCenterServername" -Port 443
2. If there is an error, check DNS name resolution