Thanks for your reply, Tony. Well I got to know whether, is there any issues related to Weblogic Service pack. 'coz When I used Service pack, I got SockectException and RollbackException sometimes, but not always. So I upgraded to Service pack 9, but I got NullPointerException. Is the performance depend on the servie pack. What is the best, optimumservice pack that I can use for weblogic 5.1 on Solaris 2.6 server. Early reply is appreciated.