Hyper-V VSS Errors

I have a Server 2012 Hyper-V host with a Server 2012 guest.

Windows Server Backup on the Hyper-V host has been reporting the the backups have been "Completed with Warnings"

The status of the backup job reads "Completed with warnings. Backup succeeded but some components backed up were inconsist..."

On the Items tab of the Details screen I see:
N: / Completed / Full
M: / Completed / Incremental
Host Component / Completed / Full

On the Errors tab of the Details screen I see:
HyperV / The component SERVER01(Backup Using Child Partition Snapshot) was skipped during the snapshot and will not be available for recovery.  Error: The writer experienced a transient error.  If the backup process is retired, the error may not reoccur.

When I run "vssadmin list writers" I get:
Writer name: 'Microsoft Hyper-V VSS Writer'
   Writer Id: {66841cd4-6ded-4f4b-8f17-fd23f8ddc3de}
   Writer Instance Id: {21751d9b-b97b-4485-9438-7208912ea8b1}
   State: [1] Stable
   Last error: Unexpected error

I've tried increasing the space allowed to VSS but the error is continuing.  Where should I look next to resolve this?