ORA-13643: The task can not be interrupted or cancelled.
Cause : Request to interrupt or cancel task execution can not be granted because the task has not reached the appropriate mode.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
User should wait for a few seconds and try again.
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.