I believe this is the reason for the ClasscastException. You are having 2 separate jar file containing the same classes (and some additional ones). I guess, you have configured a datasource (*-ds.xml) file for accessing the DB. What driver are you using there? Can you post it's contents? If you are using weblogic driver then you dont need the classes12.jar in the lib folder. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4126996#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...