"norman.richards(a)jboss.com" wrote : Are you using hotdeploy? I've seen this happen when you hotdeploy a session-based component but have an old instance of the class in the session. Thanks Norman. That fixed it. Would it be possible if this is documented. Why thise exception is thrown and some hints regarding the problem just to ease user when the encounter the same problem as I did. Best regards, View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4125043#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...