Cannot insert a resource container.
A database error has occurred.
DataAccessBEServer ResourceContainer_Insert: ExecuteReader requires an open and available Connection. The connection's current state is closed

The current workaround is to push install the Backup Exec Remote Agent via the Backup Exec button -> Installation and Licensing -> Install Agents and Backup Exec Servers on Other Servers method instead.

Veritas Corporation has acknowledged that the above-mentioned issue is present in the current version(s) of the product(s) mentioned. Veritas Corporation is committed to product quality and satisfied customers.
There are no plans to address this issue by way of a patch or hotfix in the current or previous versions of the software at the present time.
If you feel this issue has a direct business impact for you and your continued use of the product, please contact your Veritas Sales representative or the Veritas Sales group to discuss these concerns.
Push installing the Backup Exec Remote Agent by right-clicking on either the Hyper-V Host or the vCenter Server in the Backup and Restore tab and selecting Install Backup Exec Agent for Windows to Guest Virtual Machines will result in this error.

Cannot insert a resource container.