The default behavior in AS 4.0.X was to use a "legacy" remote invoker, and the default in AS 4.2 is to use a Remoting invoker. For a Remoting invoker, the ability to download classes over the network has to be enabled explicitly. For EJB3 the configuration file is .../server/default/deploy/ejb3.deployer/META-INF/jboss-service.xml (substitute your configuration for "default"), and the relevant entry is | <mbean code="org.jboss.remoting.transport.Connector" | name="jboss.remoting:type=Connector,name=DefaultEjb3Connector,handler=ejb3"> | <depends>jboss.aop:service=AspectDeployer</depends> | <attribute name="InvokerLocator">socket://${jboss.bind.address}:3873</attribute> | <attribute name="Configuration"> | <handlers> | <handler subsystem="AOP">org.jboss.aspects.remoting.AOPRemotingInvocationHandler</handler> | </handlers> | </attribute> | </mbean> | If you add a "loaderport" parameter to the InvokerLocator, Remoting will create a "classloader server" which, if a class cannot be found on the client side, will be contacted by the client side classloader. E.g., | <mbean code="org.jboss.remoting.transport.Connector" | name="jboss.remoting:type=Connector,name=DefaultEjb3Connector,handler=ejb3"> | <depends>jboss.aop:service=AspectDeployer</depends> | <attribute name="InvokerLocator">socket://${jboss.bind.address}:3873/?loaderport=4873</attribute> | <attribute name="Configuration"> | <handlers> | <handler subsystem="AOP">org.jboss.aspects.remoting.AOPRemotingInvocationHandler</handler> | </handlers> | </attribute> | </mbean> | will create a classloader server that listens on port ${jboss.bind.address}:4873. For more discussion see Section "5.5. Marshalling" of the Remoting Guide (http://labs.jboss.com/jbossremoting/docs/guide/index.html). View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4121471#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...