Hello and thank you in advance for your help. I am deploying an EAR that works on another application server. However I can't get it working on JBoss 4.0.5 due to the following issue: java.lang.LinkageError: loader constraints violated when linking org/xml/sax/ErrorHandler class I already tried to remove xalan.xml from EAR and placing them in {Default_Server_Home}/lib directory. I also tried to remove conflicting version of xerces.xml from the ear. If anyone knows how to resolve this issue I would be grateful to find out how to do it. Thank you. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3981375#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...