ORA-16631: operation requires shutdown of database/instance "string"
Cause : The Data Guard broker operation requires a shutdown of the database or instance.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
If the client has not yet done so, please shutdown all Oracle instances for the database.
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.