Hi @bug11 / tronder, that error means that you’re trying to add a slave to an ipotetical master interface inside a teaming interface (master = slave0 + slave1), but Rockstor is not able to find the master - related to new teaming utils and i haven’t had time to try it so I don’t know how it has been coded (@suman)
What I understand from this: first you need to define the teaming master than its slaves, have you done like this??
3.8-12.13 is missing a package dependency “NetworkManager-team”. It is added to the stable package and will be added to the next testing update coming soon. But until then, you can solve the problem with yum install NetworkManager-team. You will have to restart network manager with systemctl restart NetworkManager after that for it to take effect.