This is one of the errors that shouldn’t exist (mainly because it should have been noticed before the backup tried to complete)
DPM encountered a retryable VSS error. (ID 30112 Details: VssError:The writer experienced a transient error. If the backup process is retried,
the error may not reoccur.
Check the Application Event Log on for the cause of the failure. Fix the cause and retry the operation.
For more information on this error, go to http://go.microsoft.com/fwlink/?LinkId=132612.
Error Information from Data Protection Manager
Failed to create the volume shadow copy inside of virtual machine ”. (Virtual machine ID 21B191E3-516B-42F4-8BD7-601CC7C97CBC)
Looking at the Hyper-V hosting the VM I could see that Hyper-V was unable to create a snapshot of the volume
Looking in the VM there was 0 bytes free , leaving the VSS writer unable to do any work , so after expanding the drive the backup is successful
So now its time to see why the Operations Manager agent wasn’t installed on the machine.