Challenge
Veeam Backup Service account does not have enough privileges to call COM server application with specified CLSID. As a result, it is not possible to inject the VSS short-life process into the guest OS.
You can find the following error in the log:
[timestamp] <01> Info [VssGAConn] Initializing VSS guest agent connection
[timestamp] <01> Error Retrieving the COM class factory for component with CLSID {D2E3C73F-841A-46B0-A93F-956CCABD3B11} failed due to the following error: 80070005. at Veeam.Backup.VssProvider.CVssGAConnection.CreateEx(String hostIp, UInt16 hostPort, String hostUser, String hostPass, String vmVmx, String vmIpAddrs, CCredentials vmCreds)
[timestamp] <01> Error at Veeam.Backup.Core.CGuestControl..ctor(CHost host, CVm vm, CVssOptions vssOptions, CBackupTaskSession taskSess)
[timestamp] <01> Info Task operation result: 'Retrieving the COM class factory for component with CLSID {D2E3C73F-841A-46B0-A93F-956CCABD3B11} failed due to the following error: 80070005.'
Cause
An account under which the Veeam Backup Service runs does not have local Administrator privileges on the Veeam Backup server.
Solution
Make sure that the account under which the Veeam Backup Service runs is local Administrator.