[ovirt-users] NPE for GetValidHostsForVmsQuery

Hi, We're running oVirt 4.3.2. When we click on the "Migrate" button over a VM, an error popup shows up and in the ovirt-engine log we see: 2019-04-03 12:37:40,897+01 ERROR [org.ovirt.engine.core.bll.GetValidHostsForVmsQuery] (default task-6) [478381f0-18e3-4c96-bcb5-aafd116d7b7a] Query 'GetValidHostsForVmsQuery' failed: null I'm attaching the full NPE. Could someone point out what could be the reason for the NPE? Thanks.