ORA-12624: TNS:connection is already registered
Cause : An attempt to register a connection for event notification failed because the connection is already registered.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Not normally visible to the user. For further details, turn on tracing and reexecute the operation and contact Oracle Customer Support.
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.