Hyper-V virtual machine fails to start after moving the VHD files

Recently I had to replace a hard drive in one of my servers running Microsoft Hyper-V 2008 R2 which contained the virtual machine configuration and VHD files. I used robocopy to copy the data from the server drive, to a temporary drive, then replaced the drive before copying the data on to it.

Unfortunately, I forgot to copy the ACL’s as well, which caused issues when trying to start the virtual machines again. I use System Center Virtual Machine Manager, so when I tried to start my virtual machines again, I got the following error logged in the Jobs log: –

Error (12700)
VMM cannot complete the Hyper-V operation on the server.domain server because of the error: ‘Unnamed VM’ could not initialize. (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)

‘Unnamed VM’ could not read or update the virtual machine configuration because access was denied: General access denied error (0x80070005). Check the security settings on the folder in which the virtual machine is stored. (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)
 (Unknown error (0x8001))

Recommended Action
Resolve the issue in Hyper-V and then try the operation again.

In Hyper-V Manager, the following error is displayed when trying to start the same machine: –

‘SERVER’ failed to start.

Microsoft Emulated IDE Controller (Instance ID {598AFA1B-1726-44B7-8435-E00B2ACAF2B5}): Failed to Power on with Error ‘General access denied error’

IDE/ATAPI Account does not have sufficient privilege to open attachment ‘D:\Virtual Server\Virtual Machines\server\system.vhd’. Error: ‘General access denied error’

 Account does not have sufficient privilege to open attachment ‘D:\Virtual Server\Virtual Machines\server\system.vhd’. Error: ‘General access denied error’

[Expanded Information]
‘SERVER’ failed to start. (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)

‘SERVER’ Microsoft Emulated IDE Controller (Instance ID {598AFA1B-1726-44B7-8435-E00B2ACAF2B5}): Failed to Power on with Error ‘General access denied error’ (0x80070005). (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)

‘SERVER’: IDE/ATAPI Account does not have sufficient privilege to open attachment ‘D:\Virtual Server\Virtual Machines\server\system.vhd’. Error: ‘General access denied error’ (0x80070005). (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)

‘SERVER’:  Account does not have sufficient privilege to open attachment ‘D:\Virtual Server\Virtual Machines\server\system.vhd’. Error: ‘General access denied error’ (0x80070005). (Virtual machine ID 598AFA1B-1726-44B7-8435-E00B2ACAF2B5)

The issue is of course, that because the ACL’s weren’t preserved, Hyper-V can’t read the virtual machine files. Unfortunately, it’s not as simple as just adding the SYSTEM account to the root and applying permissions down, as Hyper-V R2 has it’s own security “namespace” (referred to in Microsoft documentation as the Service SID) called “NT VIRTUAL MACHINE” which contains the GUID’s for all registered virtual machines.

The easiest way to add permissions back to your virtual machines, in order to have them accessible via Hyper-V, is to use the following process on each machine (this is assuming you’re using System Center Virtual Machine Manager): –

  • Open the directory that stores your virtual machine
  • Open the “Virtual Machines” subdirectory under your virtual machine directory
  • Record the GUID as per the file name of the .xml file in this directory
  • Run icacls “<virtualmachinefolder>” /grant “NT VIRTUAL MACHINE\<virtualmachineguid>”:F /T (for example icacls “D:\Virtual Server\Virtual Machines\Server” /grant “NT VIRTUAL MACHINE\598AFA1B-1726-44B7-8435-E00B2ACAF2B5”:F /T

Now you should be able to start your virtual machine.