[ovirt-users] NullPointerException when changing compatibility version to 4.0

[Marcel Hanke]

Hi,
i currently have a problem with changing one of our clusters to compatibility 
version 4.0.
The Log shows a NullPointerException after several successful vms:
2017-07-19 11:19:45,886 ERROR [org.ovirt.engine.core.bll.UpdateVmCommand] 
(default task-31) [1acd2990] Error during ValidateFailure.: 
java.lang.NullPointerException
        at 
org.ovirt.engine.core.bll.UpdateVmCommand.validate(UpdateVmCommand.java:632) 
[bll.jar:]
        at 
org.ovirt.engine.core.bll.CommandBase.internalValidate(CommandBase.java:886) 
[bll.jar:]
        at 
org.ovirt.engine.core.bll.CommandBase.executeAction(CommandBase.java:391) 
[bll.jar:]
        at org.ovirt.engine.core.bll.Backend.runAction(Backend.java:493) 
[bll.jar:]
.....

On other Clusters with the exect same configuration the change to 4.0 was 
successfull without a problem.
Turning off the cluster for the change is also not possible because of >1200 
Vms running on it.

Does anyone have an idea what to do, or that to look for?

Thanks
Marcel