ORA-21521: exceeded maximum number of connections in OCI (object mode only)
Cause : User exceeded the maximum number of connections (255) that can be supported by an OCI environment in object mode.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Close some of existing and unused connections before opening more connections.
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.