ORA-12638: Credential retrieval failed Solution!

System Error: #1: ORA-12638: Credential retrieval failed

This problem always haunts me whenever I am working on a new installation of Oracle. Everything seems normal for few days and suddenly I can't connect to my App thanks to ORA-12638: Credential retrieval failed

Sometimes ORA-12638 can be resolved by restarting the database services in cases where Oracle on Windows is being used, but in many cases this does not work either..

So if you are still getting bugged with this pain then here is a permanent solution for the problem.

However, the following direction was given, and once administered, was a successful resolution to ORA-12638:

Please check the sqlnet.ora file in the admin folder of oracle installation path.Do not open the sample folder SQLNET.ORA. Change the following entry and try, this will work.

Original Entry - SQLNET.AUTHENTICATION_SERVICES= (NTS)

Modified Entry - SQLNET.AUTHENTICATION_SERVICES= (NONE)

Hope this was helpful.