Hi I'm having same problem. The sticky_session property is disabled (siticky_session=0) in mod_jk config. The Sessions are replicated, I can see they when I invoke the printDetails method in the jboss.cache:service=TomcatClusteringCache MBean, but fail over doesn't work properly and I see the message described above in the log... How you solved the problem? Thanks "Zwitsch" wrote : Hi, | | I set up a cluster which consists of 2 nodes of Jboss AS 4.0.5 with an Apache 2.0 lodabalancer in front. I also set up farming and session replication and all this just works fine. | | But out of my (distributable) application I am getting the following outputs: | | anonymous wrote : 15:27:26,358 INFO [CacheListener] Possible concurrency problem: Replicated version id 8 matches in-memory version for session EwvKAOhv-wpLJ+1T58te1A** | | Every call of the app I am getting this message with the counter "id x matches" increasing by 1. | What is wrong? Has this something to do with the serialization of the objects put in the session? | | The session replication though seems to work fine. Although failover works. | | Thanks | Thomas View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4039848#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...