Avamar Backup of a Windows VM fails with the error: Protocol error from VMX

Recently on a new install of Avamar version 6.1; I had a VMware Image based backup fail with error 10007. Upon further investigation of the backup job log I noticed that the snapshot failed with: A general system error occured: Protocol error from VMX. This is a good example of two very vague errors on both the backup system and the virtual infrastructure. So to further investigate we needed to look deeper into the vmware.log file…

I found the following line in the vmware.log: Toolsbackup: not enough empty nodes. Our issue in this case seemed to be that we had too many hard drives attached to this particular VM which only had 1 SCSI controller; The failing VM had 9 hard drives and only 1 controller. The fix is pretty easy and simply requires adding an additional controller to the virtual machine so that there are enough empty disk nodes in order to take the snapshot.

To add an additional controller when the virtual machine is running, add a new disk and in the Advanced Options step, change the Virtual Device Node to use another controller. If you power down the virtual machine, you can add another controller without adding a new disk. To add another controller, edit the settings of one of the existing disks and change Virtual Device Node to use a different controller.