The real reason for this is probably the user has installed jboss messaging in a non clustered app server configuration (e.g. like default), but has set clustered=true in the config file. If clustering is required, then jbm must be installed in a clustered app server config where jgroups is already available. There should be no need to copy jgroups.jar if the installation was performed correctly. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4174228#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...