ORA-19870: error reading backup piece string
Cause : This error should be followed by other errors indicating the cause of the problem.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
See other errors actions. Do not use message 19871; it is used by RMAN client for testing previous resync time when using backup/standby control file.
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.