During SOAK (failover, session replication, passivation disabled) testing, after 90 minutes JBoss logs:

[JBoss] 11:24:29,329 ERROR [CoyoteAdapter] An exception or error occurred in the container during the request processing
[JBoss] java.lang.NullPointerException
[JBoss] at org.jboss.web.tomcat.service.session.ClusteredSession.update(ClusteredSession.java:1097)
[JBoss] at org.jboss.web.tomcat.service.session.SessionBasedClusteredSession.update(SessionBasedClusteredSession.java:154)
[JBoss] at org.jboss.web.tomcat.service.session.distributedcache.impl.jbc.JBossCacheService.loadSession(JBossCacheService.java:344)
[JBoss] at org.jboss.web.tomcat.service.session.JBossCacheManager.loadSession(JBossCacheManager.java:1432)
[JBoss] at org.jboss.web.tomcat.service.session.JBossCacheManager.findSession(JBossCacheManager.java:491)
[JBoss] at org.apache.catalina.connector.Request.isRequestedSessionIdValid(Request.java:2160)
[JBoss] at org.apache.catalina.connector.CoyoteAdapter.parseSessionCookiesId(CoyoteAdapter.java:626)
[JBoss] at org.apache.catalina.connector.CoyoteAdapter.postParseRequest(CoyoteAdapter.java:551)
[JBoss] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:322)
[JBoss] at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:437)
[JBoss] at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:384)
[JBoss] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
[JBoss] at java.lang.Thread.run(Thread.java:619)

Hudson build: http://hudson.qa.jboss.com/hudson/job/as5-soak/44/