Hyper-V Virtual Machine Fails to Start Due to Missing VHDX Permissions

Issue

The virtual machine fails to start and stops after a few seconds. Hyper-V displays an error indicating that the virtual machine cannot access the virtual hard disk (VHDX) file. This issue occurred on a Windows Server 2016 Datacenter Hyper-V host.

Hyper-V VM failed to start. Failed to power on with Error 'General access denied error'. Account does not have permission to open attachment.

Cause

Check the ACL permissions on the VHDX file. In most cases, the virtual machine's security identifier (SID) is missing from the file permissions.

Compare the permissions on the affected VHDX file with those of a working virtual machine to confirm whether the required SID entry is missing.



Resolution

  1. Obtain the virtual machine's ID (VMID) using the following PowerShell command. Replace 'New Virtual Machine' with the name of the affected virtual machine:
Get-VM 'New Virtual Machine' | Select-Object VMID

  1. Navigate to the folder containing the VHDX file and grant the virtual machine account read/write permissions using icacls. Replace the VHDX file name and VMID with the values for your affected VM. 
icacls ".\port-mirror.vhdx" /grant "NT VIRTUAL MACHINE\73002f31-fd79-40b2-aaf9-cd86e6c0c295:RW"

After the correct permissions have been applied, start the virtual machine again and verify that it boots successfully.


Date Created: Saturday, 31 August 2019, 10:55 PM