PROBLEM

Backup fails with the following error message:

CAUSE

This was an improvement implemented in later versions of VM Backup for Hyper-V and for host OS’s running Windows Server 2012 R2 onwards. This change was carried out in order to better handle checkpoint files that are created during the Shadow Copy portion that were introduced in Windows Server 2012 R2 onwards.

SOLUTION

The issue here is due to the fact that you have another VHDX which contains part of the name of another VHDX for a VM in particular. To explain this further, you have a VM that has the following VHDX files attached to it:

exchange.vhdx
exchange-data.vhdx <--></-->

With the current name you won't be able to exclude that VHDX file because it contains the full name of another VHDX (the 'exchange' part) attached to this VM.

In this case if you'd like to exclude that VHDX file, you need to rename the first VHDX to something like exchange-os.vhdx for instance or else rename the second VHDX so that it doesn't contain the name of the other VHDX.