VSS event ID 8194 after installing HIT 4.6

I have seen this with a few separate customers now. Event ID Error 8194 appears on Hyper-V 2012 hosts with the HIT installed as seen below.


Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005, Access is denied.

. This is often caused by incorrect security settings in either the writer or requestor process.

Operation:

Gathering Writer Data

Context:

Writer Class Id: {e8132975-6f93-4464-a53e-1050253ae220}

Writer Name: System Writer

Writer Instance ID: {c4cafe6b-9e92-49e6-b95e-35b7cd4c0cac}


The forum below intimates this has been seen before and points to the HIT.


http://social.technet.microsoft.com/Forums/en-US/c66d3ab4-44d7-4a24-bb4b-9b20b3ed56d1/backup-of-hyperv-2012-csv-intermittent-fails-with-error-0x80042301?forum=dpmhypervbackup

It would appear a working solution is to configure removing access to the network service account, what it actually does is to stop the call to VSS, hence no access denied error is reported. The double \\ is the output from the registry export and is required.

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\VssAccessControl]
"NT Authority\\NetworkService"=dword:00000000

Didier Van Hoye, has some useful information on this...
workinghardinit.wordpress.com/.../dell-compellent-hardware-vss-provider-commvault-on-windows-server-2012-hyper-v-nodes-volume-shadow-copy-service-error-unexpected-error-querying-for-the-ivsswritercallback-interface-hr-0x80