Why did my backup job fail with 'snapshots-source-volume-busy' event type?

Backup snapshots cannot be created because the source volume is performing an operation that blocks snapshot creation.

You receive an event notification with the event type 'snapshots-source-volume-busy'.

Your backup snapshot wasn't created because the parent volume is performing an operation that blocks the locking that is needed to create the snapshots.

Wait until the volume operation is complete, and allow the next scheduled backup job to create the backup.