It seems that I didn't install the JBoss4.0.4.GA correctly. I always got the exception of no class found on org/apache/commons/fileupload/disk/DiskFileItem. In addition, when I used conversation bean to submit a form, it didn't work. However, when I changed the conversation bean to session bean, it worked. I think that I probably selected "all" on the JBoss4.0.4.GA installation(I forgot), and did not select EJB3. I will try to reinstall it again. Thank you for time.