Hyper-V backup jobs fails with error: “Working directory folders for this VM may not have been cleaned up from an earlier aborted job. These will need to be manually cleaned up before backing up this VM” (4042799)

Backup job starts and shows event for:

VM[<VM name>]: Preparing working folder for backup

VM[<VM name>]: Working directory folders for this VM may not have been cleaned up from an earlier aborted job. These will need to be manually cleaned up before backing up this VM

If the backup job contains multiple VMs, it may complete with warning/errors pointing to the VMs that were not listed in the error messages.

Temporary folder used by Hyper-V plugin for backups is not empty.  

This could happen if a previous backup job was aborted or failed and the temporary files were not deleted.

Single Hyper-V host:

1-On the Hyper-V host, locate the folder

<Netvault Installation Path>/tmp/hyperv

2-Clear the content of the /tmp/hyperv (It will contain folders corresponding to the VM that failed backup)

3-Retry the backup job.

Multiple hosts on Hyper-V cluster

1-Locate the host machine where the VM that fails the backup lives:

Job logs will show:

VM[VM name]: Working directory folders for this VM may not have been cleaned up from an earlier aborted job. These will need to be manually cleaned up before backing up this VM

On the same line the Client name will also appear.   This Client name correspond to the host which /tmp/hyperv folder needs to be cleared.

2-Clear the contents of the /tmp/hyperv folder

3-Retry the backup job.