ORA-16789: missing standby redo logs
Cause : Standby redo logs are missing and are needed for SYNC and ASYNC log transport modes.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Check the Data Guard documentation to see how to create standby redo logs.
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.