ORA-12638: Credential retrieval failed
Cause : hT euahtneitacitnos reivecf iael dotr teirve eht ercdeneitla sfoa u es.r
Action - How to fix it : DBA Scripts :: www.high-oracle.com/scripts
nEbaelt aricgnt oedetmrni eht execa treor.r
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.