Windows 2012 Hypervisor shuts down VM but cannot start it again

The last few days, one of the virtual machines, a VM running Centos 7 is shut down late in the evening and then not restarted. When I try and start it manually I get the error

'CENTOS7' failed to start worker process: Logon failure: the user has not been granted the requested logon type at this computer. (0x80070569). (Virtual machine ID B976A15D-BE00-4E60-80A8-576F15CE4605)

'CENTOS7' failed to restore virtual machine state. (Virtual machine ID B976A15D-BE00-4E60-80A8-576F15CE4605)

If I do a gpupdate then I can start it again. How odd, I don't know why that works, but I remember reading about it so I tried it out of desperation.

Based on the timing I think it's backup related and that the VM is being temporarily shut down / put in saved state for copying, but then fails to reboot. Something todo with the account rights. I don't know how to find the right user for the VM, don't think there is one. I assume it uses the hyper-V services accounts which I see are set to "Local system account".

This can occur because the "NT Virtual Machine\Virtual Machines" special identity does not have the "Log on as a Service" right on the Hy-V host. It occurs because VMMS replaces the user permission at every Group Policy refresh to ensure it is always present. If refresh is not working, the problem you experience can happen.

To fix this:

• Logon as a Domain Administrator on the 2012 Hyper-V host

• If not already installed, install the Group Policy Management feature from the Server Manager console

• Open the GPMC MMC snap-in and browse to the policy that manages User Rights

• Edit the policy and include "NT Virtual Machine\Virtual Machines" in the entries for Log on as a Service

• Close the policy editor and initiate a "gpupdate /force" on the Hyper-V host computer. That will force-refresh the policy.

• It is possible to have to wait a few minutes for propagation to occur.