Which version of richfaces and server are you using. Could you provide with some more info.Have you seen this example http://showcase.richfaces.org/richfaces/component-sample.jsf?demo=fileUpload&skin=blueSky
Maybe you can get the code from svn and try it. Please paste the stack trace as well.
Thanks for ut reply sanjeev. acctually i figured out i was getting error because of my EJB.i created different thread for it.i have given code and stack trace there.