NetWorker: NMM Hyper-v Backup fails "Failed to convert VM checkpoint of<VMName>to reference point"

Networker Module for Microsoft ( NMM) Backup of Hyper-v fails for specific  virtual machine  , other virtual machines backups are working fine.

nsrnmmsv log shows:

Date/Time PERF [1728317672]: Post-backup is completed
Date/Time Error: 
Date/Time  Failed to convert VM checkpoint of <VMNAME> to reference point.
Date/Time Error: 
Date/Time Deleting checkpoint of VM  <VMNAME>  

When Enabling Debug level, Hyper-v shellmgmt logs shows:

Datetime:Getting disk identifier for disk ~\Don't delete it\Virtual Hard Disks\System_GUID.avhdx

Datetime:In RunPowerShellScript() function, strScript Get-VHD -Path '~\Don't delete it\Virtual Hard Disks\<diskname>.vhdx' |select -Property DiskIdentifier

Datetime:Failed to get VMHardDiskDrive for the VM <VMNAME> The string is missing the terminator: '.

During backup, the following PowerShell command to get the virtual machine VHDX Identifier 

Get-VHD -Path  <VHDX_PaTH> | select -Property DiskIdentifier

If the virtual machine name or the path name has unsupported characters the backup fails.

In this case the path had Don't delete it

Change the name of the virtual machine and/or disk path , avoid using single quotes or special characters 

Note:

Please refer to Dell NetWorker Module for Microsoft for Hyper-V Guide

The Supported special characters table lists the special characters that NMM supports.
Examples of usage of special characters:

● Virtual machine name: VM@emc%1%
● VHD paths: C:\@folder\&^%
● VHD names: C:\folder\VM@emc(1).vhd
● Files and folders inside virtual machine: samplefile!@#.txt
● Folder paths: C:\@folder\&^\sample.txt
● Mount paths: C:\mountSplcharvms\!@#$%

https://www.dell.com/support/manuals/en-us/networker-module-for-microsoft/nmm_hyper_v_user_guide_19.10/supported-and-unsupported-features-for-hyper-v-backups?guid=guid-dc0011a3-bf46-4a96-974b-c79fe0109c90&lang=en-us