Joseph Hwang [http://community.jboss.org/people/aupres] created the discussion "EntityManager.remove() throws java.lang.IllegalArgumentException: Removing a detached instance ?" To view the discussion, visit: http://community.jboss.org/message/592898#592898 -------------------------------------------------------------- @Stateless public class LoginSession implements ILoginSession { @PersistenceContext(unitName="MyHome") EntityManager em; .... public Object loginFunc(Class clazz, Object primaryKey) {   // TODO Auto-generated method stub   return em.find(clazz, primaryKey); } public Object removeFunc(Serializable entity) {   // TODO Auto-generated method stub   em.remove(entity);   return entity; } ..... } bean codes are like above. in JSP file ILoginSession login = ctx.lookup(LoginSession/remote); Members erase = (Members)login.loginFunc(Members.class,"father"); out.println(erase.toString()); // It works to this lines login.removeFunc(erase); // but this line thows Exception EntityManager.remove() fuction throws "java.lang.IllegalArgumentException: Removing a detached instance" I need your advice.. Best Regards....^_^ -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/592898#592898] Start a new discussion in EJB3 Development at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]