anonymous wrote : * servlet-api.jar | * jbossall-client.jar | * jboss-j2ee.jar | * jboss-ejb3-proxy-client.jar Remote these from the (both) application packaging. You don't need these since they are already shipped in AS. anonymous wrote : One on a virtual machine (ubuntu-jeos, jboss5.1.0 GA). The other one on my windows (winXP, jboss5.0.1 GA). So your server is 5.0.1.GA and the client is 5.1.0.GA. I remember there was an incompatibility between AS version in the 5.x series. Let me check which exact version caused the incompatibility. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4242644#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...