While attempting to upgrade NVBU on all clients, the guided configuration does not propose a list of existing clients to upgrade.
When clicking "Allow existing NetVault client installations to be upgraded" > then "Choose Machines" pull up menu, there is only 3 options:
> By FQDN or IP
> From Active Directory
> From a file I
The "From existing NetVault clients" option is missing when the NetVault Package is selected but appears when an npk is selected.
To upgrade several clients using the Push Install engine, you can search and select the clients to upgrade by searching the Active Directory or by building a file with a list of clients to upgrade. See the NVBU Administrator's guide for more details on these options.
Bug 31488 will be fixed in a future version of NVBU.