I recently received this error in Backup Exec 2010 when I selected to back up a Template. This template existed on a VMware ESXi 5.1 cluster. I was using the Agent for VMware and backing up through VCenter using the NBD method. Being a template, it was offline and did not have a Remote Agent installed.
The problem I discovered was that I had used a special character in the building of this machine. Being that this was a template, which I planned to deploy many virtual machines from, I wanted to easily attach a date in its name. Mostly, I did this so I knew how far out it was on Windows Updates. So I named by Template, “Base Win2K8 SP1 (6/20/13)”.
The problem here was the forward slash “/”. In VMware this date became “(6%2f20%2f13)”. Not only did VMware change the name of the template itself (which is easily fixed with a right click and choosing rename) but it also named all the templates required files the same way.
Now this is considerably trickier and can not be changed through the VMware Infrastructure Client. To change the names of the disks you would need to download and install the vCLI, which is freely available in the VMware community. The process for renaming virtual machines required files with the vCLI is available thorough the VMware KB article listed below.