There is a never ending warn log message printed after a cluster node rejoins, after a shutdown:

03:43:15,831 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:15,831 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:15,887 INFO [org.jboss.as.server] (Controller Boot Thread) JBAS018559: Deployed "wildfly-cluster-ha-singleton-service.jar" (runtime-name : "wildfly-cluster-ha-singleton-service.jar")

03:43:15,895 INFO [org.jboss.as] (Controller Boot Thread) JBAS015961: Http management interface listening on http://127.0.0.1:10090/management

03:43:15,895 INFO [org.jboss.as] (Controller Boot Thread) JBAS015951: Admin console listening on http://127.0.0.1:10090

03:43:15,896 INFO [org.jboss.as] (Controller Boot Thread) JBAS015874: WildFly 8.0.1.Final-SNAPSHOT "WildFly" started in 4855ms - Started 345 of 437 services (171 services are lazy, passive or on-demand)

03:43:16,332 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:16,332 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:16,833 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:16,834 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:17,335 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:17,336 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:17,835 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:17,836 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:18,335 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:18,336 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:18,837 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:18,838 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:19,339 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:19,340 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:19,840 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:19,840 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:20,003 INFO [org.jboss.as.quickstarts.cluster.hasingleton.service.ejb.SchedulerBean] (EJB default - 1) HASingletonTimer: Info=HASingleton timer @nodeTwo Sat Feb 22 03:43:15 WET 2014

03:43:20,003 INFO [org.jboss.as.quickstarts.cluster.hasingleton.service.ejb.SchedulerBean] (EJB default - 2) HASingletonTimer: Info=HASingleton timer @nodeTwo Sat Feb 22 03:43:15 WET 2014

03:43:20,341 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:20,342 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:20,841 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:20,842 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:21,342 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:21,342 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:21,842 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:21,843 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:22,343 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:22,344 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:22,845 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:22,845 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:23,345 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:23,346 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

03:43:23,846 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/server: dropping unicast message to wrong destination a1fdbb88-a500-483d-7405-70c93a8ab740

03:43:23,846 WARN [org.jgroups.protocols.TP$ProtocolAdapter] (INT-1,shared=udp) JGRP000031: nodeTwo/ejb: dropping unicast message to wrong destination f567dfca-cdad-2555-0e3b-22c8ebded75b

This can be seen using WildFly's cluster-ha-singleton quickstart (github project wildfly/quickstart). Just follow quickstart’s readme till point 4 of "Check the timer" section, and after stop node2 (not node1) start it gain.