ORA-12839: cannot modify an object in parallel after modifying it
Cause : Within the same transaction, an attempt was made to perform parallel modification operations on a table after it had been modified. This is not permitted.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Rewrite the transaction or break it up into two transactions: one containing the parallel modification and the second containing the initial modification operation.
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.