Hello Arik,

        we have upgrade one of our oVirt engines to 4.2.1 (from 4.1.9)
        and afterwards all nodes too. The cluster compatibility level
        has been set to 4.2.

        Now we can't start a VM after it has been powered off. The only
        hint we found in engine.log is:

        2018-03-07 14:51:52,504+01 INFO
        [org.ovirt.engine.core.vdsbroker.UpdateVmDynamicDataVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] START,
        UpdateVmDynamicDataVDSCommand(
        UpdateVmDynamicDataVDSCommandParameters:{hostId='null',
        vmId='a7bc4124-06cb-4909-9389-bcf727df1304',
        vmDynamic='org.ovirt.engine.co
        <http://org.ovirt.engine.co>re.common.businessentities.VmDynamic@491983e9'}),

        log id: 7d49849e
        2018-03-07 14:51:52,509+01 INFO
        [org.ovirt.engine.core.vdsbroker.UpdateVmDynamicDataVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] FINISH,
        UpdateVmDynamicDataVDSCommand, log id: 7d49849e
        2018-03-07 14:51:52,531+01 INFO
        [org.ovirt.engine.core.vdsbroker.CreateVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] START, CreateVDSCommand(
        CreateVDSCommandParameters:{hostId='0add031e-c72f-473f-ab2f-4f7abd1f402b',
        vmId='a7bc4124-06cb-4909-9389-bcf727df1304', vm='VM
        [prod-hub-201]'}), log id: 4af1f227
        2018-03-07 14:51:52,533+01 INFO
        [org.ovirt.engine.core.vdsbroker.vdsbroker.CreateBrokerVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] START,
        CreateBrokerVDSCommand(HostName = prod-node-210,
        CreateVDSCommandParameters:{hostId='0add031e-c72f-473f-ab2f-4f7abd1f402b',
        vmId='a7bc4124-06cb-4909-9389-bcf727df1304', vm='VM
        [prod-hub-201]'}), log id: 71dcc8e7
        2018-03-07 14:51:52,545+01 ERROR
        [org.ovirt.engine.core.vdsbroker.vdsbroker.CreateBrokerVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] Failed in
        'CreateBrokerVDS' method, for vds: 'prod-node-210'; host:
        'prod-node-210': null
        2018-03-07 14:51:52,546+01 ERROR
        [org.ovirt.engine.core.vdsbroker.vdsbroker.CreateBrokerVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] Command
        'CreateBrokerVDSCommand(HostName = prod-node-210,
        CreateVDSCommandParameters:{hostId='0add031e-c72f-473f-ab2f-4f7abd1f402b',
        vmId='a7bc4124-06cb-4909-9389-bcf727df1304', vm='VM
        [prod-hub-201]'})' execution failed: null
        2018-03-07 14:51:52,546+01 INFO
        [org.ovirt.engine.core.vdsbroker.vdsbroker.CreateBrokerVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25)
        [f855b54a-56d9-4708-8a67-5609438ddadb] FINISH,
        CreateBrokerVDSCommand, log id: 71dcc8e7
        2018-03-07 14:51:52,546+01 ERROR
        [org.ovirt.engine.core.vdsbroker.CreateVDSCommand]
        (EE-ManagedThreadFactory-engine-Thread-25) [f855b5
        4a-56d9-4708-8a67-5609438ddadb] Failed to create VM:
        java.lang.NullPointerException
        at
        org.ovirt.engine.core.vdsbroker.builder.vminfo.LibvirtVmXmlBuilder.lambda$writeInterfaces$23(LibvirtVmXmlBuilder.java:1066)
          [vdsbroker.jar:]

        [...]

        But this doesn't lead us to the root cause. I haven't found any
        matching bug tickets in release notes for upcoming 4.2.1. Can
        anyone help here?


    What's the mac address of that VM?
    You can find it in the UI or with:

    select mac_addr from vm_interface where vm_guid in (select vm_guid
    from vm_static where vm_name='<vm_name>');


Actually, different question - does this VM has unplugged network interface?

The VM has two NICs. Both are plugged.

The MAC addresses are 00:1a:4a:18:01:52 for nic1 and 00:1a:4a:36:01:67 for nic2.

Regards

Jan