Hyper-V backup of VM fails with "Virtual machine does not have valid vhd chains and will not be backed up with image level backup"

Hyper-V backups of certain VMs may fail with messages similar to the following:

avhypervvss Warning <42496>: Virtual machine 'EMC <GUID>' has one or more virtual disks with same ID and will not be backed up with image level backup.
...
avhypervvss Error <43105>: Virtual machine 'EMC' does not have valid vhd chains and will not be backed up with image level backup
avhypervvss Warning <41605>: The following Virtual Machines have failed:
avhypervvss Warning <41604>: [1] EMC <GUID>

This problem occurs when one of the virtual hard drives that are attached to the virtual machine was created by copying the contents of a physical hard drive. In this scenario, the new virtual hard drive contains the same disk signature as the physical drive in the parent partition. During a backup process that involves Hyper-V VSS Writer, the virtual hard disks are mounted in the parent partition. This process fails for the affected virtual machines because of the disk signature collision.

1. Power off the affected VM.

2. For each of the VHDX files that are attached to the VM, run this cmdlet using PowerShell prompt (run as Administrator):

Get-VHD -path "<<directory of the VHD files>>"

Example:  Get-VHD -path "D:\Hyper-V\EMC.vhdx"
                 Get-VHD -path "D:\Hyper-V\EMC1.vhdx"

3. Check the "DiskIdentifier" field for each VHD. If they are not unique, change the disk IDs so that they are different from each other.

Set-VHD -ResetDiskIdentifier -Path "location of VHDX file"

That changes the disk identifier attribute on the VHDX file. Do this for the other VHDX files that are attached to the affected VM.

4. Power the VM back on.

5. Open PowerShell prompt and run the following command:

Get-VHD -path "<<directory of the VHD files>>"

Do this for each of the VHDX files for the affected VM(s) and confirm that the disk identifier value is different for each file.