Invalid configuration for device ’0′ when enabling a NIC in vSphere

Suddenly a VM was unreachable on all interfaces. Upon investigation, I saw that none of the NIC's were set to connected:







When I tried to enable them again I got Invalid configuration for device ’0′:

Some googling led to a simple solution, which is to restart the management agents:

service mgmt-vmware restart

and

service vmware-vpxa restart

Good to know. Thanks go to the cupfighters for investigating it deeper and leading me to the answer.