I have an java ee application with a remote business interface:

public interface RegisterRemote {
 public void createUser(User user);
 public User findUser(long id);
}

and a stateless session bean:

@javax.ejb.Stateless
@javax.ejb.Remote(RegisterRemote.class)
public class RegisterBean implements RegisterRemote {
 @javax.persistence.PersistenceContext(unitName="carDatabase")
 private javax.persistence.EntityManager em;

 public void createUser(User user) {
 em.persist(user);
 }

 public User findUser(long id) {
 return em.find(User.class, id);
 }
}

and my client looks so:

public class Client {
 static public void main(String[] args) {
 try {
 Context jndiContext = getInitialContext();
 Object ref = jndiContext.lookup("RegisterBean/remote");
 RegisterRemote dao = (RegisterRemote)
 PortableRemoteObject.narrow(ref, RegisterRemote.class);

 Customer customer_1 = new Customer();
 customer_1.setFirstName("Francis");
 customer_1.setLastName("Pouatcha");
 customer_1.setUsername("francis.pouatcha");
 customer_1.setPassword("franc123Poutacha");
 customer_1.setEmail("fancis.pouatcha@gmail.de");
 dao.createUser(customer_1);

 Customer customer_2 = (Customer) dao.findUser(1);
 System.out.println(customer_2.getFirstName());
 System.out.println(customer_2.getLastName());
 System.out.println(customer_2.getUsername());
 System.out.println(customer_2.getPassword());
 System.out.println(customer_2.getEmail());

 } catch ( NamingException ne ) {
 ne.printStackTrace();
 }
 }
 private static Context getInitialContext() throws NamingException {
 java.util.Properties properties = new java.util.Properties();
 properties.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
 properties.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");
 properties.put(Context.PROVIDER_URL, "jnp://localhost:1099");
 return new javax.naming.InitialContext(properties);
 }
}

and then when I run this client for the first time this do all things fine. But when I change the annotion of the session bean to @javax.ejb.Stateful then I get this error:

[java] Exception in thread "main" javax.ejb.EJBException: java.lang.IllegalArgumentException: Wrong target. class de.mathema.slsb.RegisterBean for public void de.mathema.slsb.RegisterBean.createUser(de.mathema.domain.User)
 [java] at org.jboss.ejb3.tx.Ejb3TxPolicy.handleExceptionInOurTx(Ejb3TxPolicy.java:69)
 [java] at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:83)
 [java] at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:197)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:76)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:78)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:47)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:227)
 [java] at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
 [java] at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
 [java] at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:828)
 [java] at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:681)
 [java] at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:358)
 [java] at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:398)
 [java] at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:239)
 [java] Caused by: java.lang.IllegalArgumentException: Wrong target. class de.mathema.slsb.RegisterBean for public void de.mathema.slsb.RegisterBean.createUser(de.mathema.domain.User)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.handleErrors(MethodInvocation.java:141)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:116)
 [java] at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
 [java] at org.jboss.ejb3.interceptor.EJB3InterceptorsInterceptor.invoke(EJB3InterceptorsInterceptor.java:63)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.entity.TransactionScopedEntityManagerInterceptor.invoke(TransactionScopedEntityManagerInterceptor.java:54)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.AllowedOperationsInterceptor.invoke(AllowedOperationsInterceptor.java:47)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:79)
 [java] at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:197)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.tx.TxPropagationInterceptor.invoke(TxPropagationInterceptor.java:76)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.stateless.StatelessInstanceInterceptor.invoke(StatelessInstanceInterceptor.java:62)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:78)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:47)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.stateless.StatelessContainer.dynamicInvoke(StatelessContainer.java:227)
 [java] at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106)
 [java] at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82)
 [java] at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:828)
 [java] at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:681)
 [java] at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:358)
 [java] at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:398)
 [java] at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:239)
 [java] at org.jboss.remoting.RemoteClientInvoker.invoke(RemoteClientInvoker.java:190)
 [java] at org.jboss.remoting.Client.invoke(Client.java:525)
 [java] at org.jboss.remoting.Client.invoke(Client.java:488)
 [java] at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:55)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:61)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:55)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:78)
 [java] at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 [java] at org.jboss.ejb3.stateless.StatelessRemoteProxy.invoke(StatelessRemoteProxy.java:102)
 [java] at $Proxy0.createUser(Unknown Source)
 [java] at de.mathema.clients.Client.main(Client.java:40)

But when I restart the server and then run my client for the second time this work fine.

Can somebody tells me what is here the problem, because I know that jboss as is a hot-deployment server that can inspect that something have been changed.

Thanks.