Avamar: Hyper-V backups failing with "Unable to get the VMs for backup."

Hyper-V cluster backups fail with errors similar to the following below:
 

avhypervvss Error <43381>: Unable to get the VMs for backup.
avhypervvss Info <0000>: --------------------Start [EMC Avamar Plug-in Service for Windows] log ------------------

avhypervvss Info <0000>: Calling Thread identity: NT AUTHORITY\SYSTEM

avhypervvss Info <0000>: SharedStoragePath is not set

avhypervvss Info <0000>: Exception in GetTargetVMsForRCT Failed to validate shared storage path

avhypervvss Info <0000>: ----------------------End [EMC Avamar Plug-in Service for Windows] log -------------------

avhypervvss Info <0000>: 
avhypervvss Error <41732>: Failed to collect the list of remote VMs
avhypervvss Error <41581>: Failed to backup targets. Unable to expand targets.
avhypervvss Error <41662>: Failed to validate and expand the targets.
avhypervvss Error <41659>: Backup did not complete successfully
avhypervvss Info <9772>: Starting graceful (staged) termination, Backup did not complete successfully (wrap-up stage)

The shared storage parameter has not been configured on the Hyper-V cluster.
This cluster parameter is required for the latest Hyper-V VSS hotfixes for v19.3, 19.4, 19.7 and 19.8.
The default versions of the Hyper-V VSS plug-in (19.4 and higher) also requires the parameter to be configured beforehand.

To configure the shared storage path parameter for the Hyper-V cluster, follow the procedures documented in the following knowledge base article:

https://www.dell.com/support/kbdoc/en-us/000211510

Once the parameter has been configured on the Hyper-V cluster, retry the Hyper-V backup.

IMPORTANT:  This is a one-time change during the lifetime of the Hyper-V cluster. It must be carefully planned and set on a CSV or SMV shared storage accessible to all nodes. If unsure about how to make this change, consult with the Hyper-V administrator before proceeding.

List of Hyper-V plug-in's latest cumulative hotfixes:

• Avamar Plugin version 19.4.100-124 HF 337285
• Avamar Plugin version 19.7.100-82 HF 337450
• Avamar Plugin version 19.8.100-83 HF 337654

Note: For Avamar Hyper-V plug-in version 19.4.100-116 or below, upgrade to 19.4.100-124 or later and apply the corresponding HF.