I have my own customer MBeans (which of course I started from the sample.) I also am getting this same exception whenever unbind is called. Note this error occurs by doing an Apply in the MBean viewer (8082); I think that is because setJNDIName is being called. My MBeans otherwise work fine; strangely, the Apply successfully makes the changes, in spite of the exception. My EJBs can find the MBean, so the name must be right.