ORA-23344: constraint (string.string) does not exist
Cause : A null, misspelled or nonexistent constraint was specified when registering a uniqueness conflict.
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
Register a named constraint for the specified table.
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.