Hello, i have the same problem (jboss-5.1.0.GA-jdk6 & jdk6 (& debian linux)). i got the "setProperty must be overwritten...."-Exception when i access my simple stateless session bean webservice. this service is working without problems under jboss-5.1.0.GA & jdk5. this is a part of classes loaded at a jboss start (perhaps this helps): | [Loaded javax.xml.soap.SOAPMessage from /home/guido/appz/jboss-5.1.0.GA/lib/endorsed/jbossws-native-saaj.jar] | [Loaded org.jboss.ws.core.soap.SOAPMessageImpl from jar:file:/home/guido/appz/jboss-5.1.0.GA/server/default/deployers/jbossws.deployer/jbossws-native-core.jar!/] | thx for your help, guido View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4244912#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...