AVVI backup fails with error "Unable to open a disk of the virtual machine. VixDiskLib_Open() reported the error: You do not have access rights to this file".

Problem

Agent for VMware Virtual Infrastructure (AVVI) fails with the error below:

Error Message

Error from Job Log:

Final error: 0xe0009585 - Unable to open a disk of the virtual machine.

Unable to open a disk of the virtual machine.   VixDiskLib_Open() reported the error: You do not have access rights to this file.

Error in beremote debug log: 

[fsysshared]        - VDDK-Warn: [NFC ERROR] NfcNewAuthdConnectionEx: Failed to connect to peer. Error: Host address lookup for server esx_host.intra.domain.com failed: The requested name is valid, but no data of the requested type was found
[fsysshared]        - VDDK-Log: NBD_ClientOpen: Couldn't connect to esx_host.DOMAIN:902 Host address lookup for server esx_host.intra.domain.com failed: The requested name is valid, but no data of the requested type was found
[fsysshared]        - VDDK-Log: DISKLIB-LINK  : "vpxa-nfc://[DATASTORE NAME] VM_NAME/VM_NAME_1.vmdk@esx_host.DOMAIN:902!52 6b bd d7 c0 14 9f 6e-1d 1d ea 36 f8 74 27 b0" : failed to open (NBD_ERR_NETWORK_CONNECT). 

NOTE: If beremote shows  

VDDK-Log: NBD_ClientOpen: Couldn't connect to ESXFQDN:902 Cannot connect to host ESXFQDN: No connection could be made because the target machine actively refused it.
This may happen if port 902 is being blocked.

Cause

 This issue occurs because Backup Exec does not have access to the ESX Host.

vCenter provides Backup Exec with a central point of integration to automatically discover and protect Guest virtual machines across multiple ESX hosts even when Guest virtual machines are being relocated via vMotion during a backup between ESX hosts. This makes setting up and configuring backups of large numbers of Guest virtual machines easy regardless of which ESX server is currently hosting them.

During the backup process Backup Exec will need to establish connection to the ESX host(s) to gather metadata.  As such, an open connection between the Backup Exec server and the ESX host(s) is necessary.

The port being used to communicate between the Media Server and the ESX server will need to be opened, port 902 is default.

Solution

Following steps can be tried to fix the issue:

1. Backup Exec must be able to connect directly to the ESX host(s) for backup and restore operations to complete successfully.
2. Check whether "VM template" is in the selection list, if so, uncheck it and re run the backup.
3. Open port 902 for ESX communication.