Greetings, My application is creating entity beans dynamically, so, when i create i new entity bean i must update the Ejb3Configuration to let it know there is a new bean, i make this using the method 'addAnnotatedClass(Class clazz)' and 'buildMappings()'. I have several EntityManagerFactory, created using the clas Ejb3Configuration , using the method (createEntityManagerFactory()). The problem is how to update the EntityManagerFactory that has been already created, before the update of the Ejb3Copnfiguration. If i want to do it, i have to create a new EntityManagerFactory from the Ejb3Configuration updated. Example: Ejb3Configuration ejb3Configuration = new Ejb3Configuration(); Properties p = new Properties(); //Config properties ....... ejb3Configuration.addProperties(p); //add some entities ejbConfiguration.addAnnotatedClass(Entity1.class); ejbConfiguration.addAnnotatedClass(Entity2.class); //Create the factory EntityManagerFactory factory = ejbConfiguration.createEntityManagerFactory(); ..... ..... ..... Then in some point my application needs to know about a new entity bean so i add it to the configuration i've been using: ejbConfiguration.addAnnotatedClass(EntityBean3.class); EntityManager entityManager = factory.createEntityManagerFactory(); //Use this EntityManager to persist the new entity entityManager.persist([instance of EntityBean3]); In this point i got the error: EntityBean3 not mapped, that is because the factory is not synchronized with the Ejb3Configuration. How can i make this sync ?. I'm working creating a new EntityManagerFactory everytime the application generates a new entity bean, but i think that is really ugly, not to mention the performance problems for the application. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3956813#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...