I use glusterfs as storage. When I tried to create a virtual disk for a vm, I got the following error in UI logs. 

ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-48) [] Permutation name: B003B5EDCB6FC4308644D5D001F65B4C

ERROR [org.ovirt.engine.ui.frontend.server.gwt.OvirtRemoteLoggingService] (default task-48) [] Uncaught exception: : com.google.gwt.core.client.JavaScriptException: (TypeError) 

 __gwt$exception: <skipped>: a is undefined

        at Unknown._kj(Unknown Source)

        at Unknown.JUq(Unknown Source)

        at Unknown.Fbr(Unknown Source)

        at Unknown.Hno(Unknown Source)

        at Unknown.t0n(Unknown Source)

        at Unknown.w0n(Unknown Source)

        at Unknown.q3n(Unknown Source)

        at Unknown.t3n(Unknown Source)

        at Unknown.S2n(Unknown Source)

        at Unknown.V2n(Unknown Source)

        at Unknown.bMe(Unknown Source)

        at Unknown.V7(Unknown Source)

        at Unknown.k8(Unknown Source)

        at Unknown.czf/c.onreadystatechange<(Unknown Source)

        at Unknown.Ux(Unknown Source)

        at Unknown.Yx(Unknown Source)

        at Unknown.Xx/<(Unknown Source)

        at Unknown.anonymous(Unknown Source)