We have over 6000 VMs in the cluster with 100 running is there a way to delay updating the VMs and update the cluster compatibility level to 4.2 then update the VMs in batches? Thanks, Paul S.

I'm experiencing the same issue after upgrading from 4.1 to 4.2.4 Cluster compatibility upgrade to 4.2 fail with error "Failed to update Host cluster". In engine.log I can see the following ERROR lines: 2018-07-27 14:16:29,017+02 ERROR [org.ovirt.engine.core.bll.UpdateVmCommand] (Transaction Reaper Worker 0) [] Transaction rolled-back for command 'org.ovirt.engine.core.bll.UpdateVmCommand'. 2018-07-27 14:16:29,017+02 ERROR [org.ovirt.engine.core.bll.UpdateClusterCommand] (Transaction Reaper Worker 0) [] Transaction rolled-back for command 'org.ovirt.engine.core.bll.UpdateClusterCommand'. 2018-07-27 14:16:29,297+02 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (default task-15) [52696305] EVENT_ID: SYSTEM_FAILED_UPDATE_VM(252), Failed to Update VM CRLABOV-037-33 that was initiated by system. 2018-07-27 14:16:29,307+02 ERROR [org.ovirt.engine.core.bll.CommandsFactory] (default task-15) [] An exception has occurred while trying to create a command object for command 'UpdateVm' with parameters 'VmManagementParametersBase:{commandId='748892c9-7fc5-4dda-b0da-a407765e2a8c', user='null', commandType='Unknown', vmId='cf8fec91-a8aa-43d7-9c58-f53829249470'}': WELD-000049: Unable to invoke protected final void org.ovirt.engine.core.bll.CommandBase.postConstruct() on org.ovirt.engine.core.bll.UpdateVmCommand@52b30ee2 2018-07-27 14:16:29,311+02 ERROR [org.ovirt.engine.core.bll.CommandsFactory] (default task-15) [] Exception: java.lang.IllegalStateException: Transaction Local transaction (delegate=TransactionImple < ac, BasicAction: 0:ffffac15fa64:3d3ee80d:5b5b0064:59cf status: ActionStatus.ABORTED >, owner=Local transaction context for provider JBoss JTA transaction provider) is not active STATUS_ROLLEDBACK 2018-07-27 14:16:29,368+02 ERROR [org.ovirt.engine.core.bll.UpdateClusterCommand] (default task-15) [] Command 'org.ovirt.engine.core.bll.UpdateClusterCommand' failed: null 2018-07-27 14:16:29,368+02 ERROR [org.ovirt.engine.core.bll.UpdateClusterCommand] (default task-15) [] Exception: javax.ejb.EJBTransactionRolledbackException 2018-07-27 14:16:29,402+02 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (default task-15) [] EVENT_ID: USER_UPDATE_CLUSTER_FAILED(812), Failed to update Host cluster (User: pavanm@unicloudidattica.local(a)unicloudidattica.local-authz) Monitoring the engine.log with tailf I observed the task failing every time on a different VM. The cluster is very huge with more then 700 VMs. Thank you, Stefano Stagnaro.