1. Servicenow The Rpc Server Is Unavailable. (exception From Hresult: 0x800706ba)

Hi guys, would like to share a recent issue with VSS-aware processing

Winword RPC server is unavailable. (Exception from HRESULT: 0x800706BA) Please Sign up or sign in to vote. RPC server is unavailable.

Environment: Veeam 7.0 running on Windows 2012 R2 and backing up a couple of vSphere 5.1 U1 hosts
All Windows 2008 and Windows 2008 R2 VM where saved successfully with VSS-aware processing, all Windows XP and Windows 2003 VM failed with error
Failed to inventory guest system: Veeam Guest Agent is not started
Failed to prepare guest for hot backup. Error: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)
Error: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)
and sometimes error
Failed to inventory guest system: Veeam Guest Agent is not started
Failed to prepare guest for hot backup. Error: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
Error: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
I was using the Administrator user of the AD domain to perform VSS-aware backup
I spent a full day trying to restrict RPC ports (http://www.veeam.com/kb1174), disable firewall, disable antivirus, check DNS name resolution, etc etc but no way. Network configuration (subnet, gateway) was the same on Windows 2008 / 2008 R2 VM and Windows XP / 2003 VM, but only the latter failed (maybe a screwed up patch from Microsoft on those systems?)
At the end I found this workaround to be success: http://www.veeam.com/KB1671
Added new registry value that reverses the sequence of application-aware processing, making jobs try network-less processing mode before network one.
HKEY_LOCAL_MACHINESOFTWAREVeeaMVeeam Backup and Replication

Servicenow The Rpc Server Is Unavailable. (exception From Hresult: 0x800706ba)

DWORD: InverseVssProtocolOrder
Value = 1
To disable (default behavior), value is 0 (false)
After changing this registry key all VM where saved successfully with VSS-aware processing
I'm wondering why Veeam didn't try automatically the VIX api method to perform VSS-aware processing when seeing the the network mode failed
Cheers
Marco