ORA-24756: transaction does not exist
Cause : An invalid transaction identifier or context was used or the transaction has completed.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Supply a valid identifier if the transaction has not completed and retry the call.
Well, the reason for above error is that i have taken the above script from a 11g database and running it on 10g database. 11g has bring some changes in password management. Below code is executed on 11g and user created successfully, which is expected result.