Resolved the problem and just for completeness am posting the cause. This was a user error. (Surprise!) There were 2 problems: 1) I was using the wrong method for my search. I was using query.setParameter with a list as on object. It works a lot better with using query.setParameterList. This fixed the original exception, but caused another exception to be thrown having to do with the RoleImpl. 2) In my query I was sending in a set of org.jboss.portal.identity.Role objects as the parameter to my query. Since my hibernate configuration didnt have any references to Role interfaces (implemented by RoleImpl) , it didnt know what to do with them. Once I changed the parameters from a set of Roles to a set of Strings (All I really wanted was the names of the roles anyway) everything cleared up. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3977651#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...