Hi, I use JBoss 4.0.5 GA with EJB 3 with Eclipse. I have an EJB- project and a Web-project. They are (for now) running in the same VM in JBoss. When I get my SessionBean - stub in my web app (via Naming service) and try to cast it to the remote interface, I get a ClassCastException. I already found out that the problem lies in the fact that 2 remote interface class files are deployed. It's described in the wiki http://wiki.jboss.org/wiki/Wiki.jsp?page=CommonHurdlesAndDifficultiesYouM... The wiki presents 3 solutions: 1. remove the duplicate interface from one of the deployed libs. I found out that this works in principle. My problem with this is, that I don't use an Ant build file where I could simply exclude the file. I use Eclipse to generate the EAR / WAR archive (with Export to... ). Removing the remote interface from the web-archive afterwards solves the problem with the ClassCastException, but is much too time-consuming . 2. run your application in different VMs -> not a good solution for me right now 3. enable CallByValue for JNDI unfortunately this is not elaborated in the Wiki. From other resources, I found out that some changes to config files should be made, but the descriptions did not fit to JBoss 4.0.5 (obviously the conf-files have been reorganized). I tried to implement the changes all the same but it did not work! Next I remembered that during the Jboss install there was an option to "Enable deployment isolation" which sounded like it could solve the problem. So I reinstalled JBoss with this option activated. Unfortunately this did not solve the problem neither. One more strang fact: the ClassCastException only occurs if the EJB is a stateful SessionBean. With a stateless SessionBean I have no problem. I have already spent way too much time with this problem, so I would be very grateful if s.o. could help me with this. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3991904#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...