GVM1218E Your selections have caused the backup task definition to require count characters, which exceeds the 512 character limit. This can be caused by a long virtual machine exclude list, which is the list of all VMs under host(s) that were not selected. Either select more VMs under selected hosts or de-select the newly added virtual machines checkbox.
Explanation
When the newly added virtual machines checkbox is selected, the resulting backup task must list all unselected VMs for hosts that are partially selected. The backup task definition has a 512 character limit, and the combination of selected items and excluded VMs exceeds this limit.
Administrator response
De-select the newly added virtual machines checkbox or create multiple backup tasks with less selected items per task.