[2018-03-23T08:41:16,604][INFO ][o.e.d.z.ZenDiscovery ] [zld01767.vci.att.com-01] failed to send join request to master [{roacamu02.gcsc.att.com-01}{C1mZNUdPT460CGjpZ7C_6w}{W4ztO6y_SPagu1cVsNProQ}{135.89.30.224}{135.89.30.224:9300}{ml.enabled=true}], reason [RemoteTransportException[[roacamu02.gcsc.att.com-01][135.89.30.224:9300][internal:discovery/zen/join]]; nested: IllegalStateException[failure when sending a validation request to node]; nested: RemoteTransportException[[zld01767.vci.att.com-01][135.49.206.48:9300][internal:discovery/zen/join/validate]]; nested: IllegalArgumentException[Unknown NamedWriteable [org.elasticsearch.cluster.metadata.MetaData$Custom][licenses]]; ]
SOLVED - Had to install x-pack on the new node