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how to resolve ORA-12638: Credential retrieval failed

Posted by Pavan DBA on May 19, 2010

Hi Friends, today i faced very nasty situation in establishing network connection with Oracle database.

I created a user as per request from application team and i got response that they are not able to connect. when analyzing i found tnsping is not working.

I started looking at tnsnames.ora and compared that with what is there in server and its same. so as next step i looked at SQLNET.ORA file and added following line to make sure both the machines are in same domain


Still nothing worked. Then i tried telnet from client machine and realized that 1521 port is blocked at firewall level.

Once firewall team provided access, tnsping worked but it throwed ORA-12638 : credential retrieval failed error

I found following line in sqlnet.ora file


Then i modified the above line as below and it started working


Reason : 

Oracle client attempt to use your current Windows domain credentials to authenticate you with the Oracle server. This could fail for a couple of reasons:

– The Oracle server is not configured to support Windows authentication
– The credentials you use to login to your local machine are not sufficient to allow you to login to the server.

In my case, it was the later. This failed because I was logged on to my local machine using my normal domain credentials rather than my administrator account. 

20 Responses to “how to resolve ORA-12638: Credential retrieval failed”

  1. Ethan N said

    For some reason, connecting to the DB worked flawlessly until yesterday, then today it stopped working.
    setting SQLNET.AUTHENTICATION_SERVICES from NTS to NONE seems to have worked 🙂

  2. Eugene said

    This still works in May 2016. I had a customer of my company which needed my help in resetting a database parameter. This company was running an older ( Oracle database. I tried logging into their database using the correct password for SYS and also for SYSTEM. Neither would work – they gave ORA-12638 errors. I applied the change recommended by Pavan to their SQLNET.ora file – the next login attempts, for both SYSTEM and SYS were successful. Thanks!

  3. sachin said

    Thanks, after making the above changes, now its working fine 🙂

  4. Elnur said

    Thank you, it helped

  5. Manoj Patel said

    Thanks it’s work fine

  6. farhan parkar said

    Thanks it helped me 🙂

  7. Murali said

    Thank u………!!!!!!!!!!!

  8. Sandanuwan said

    Thank you! It works!

  9. Pankaj said

    Great !!! Thanks for the solution

  10. Jeff said

    Thanks! This has been very helpful today!

  11. Rony said

    A great solution , thanks

  12. siva kumar kotha said

    Excellent solution.. Thank you.

  13. Musician said

    Thanx Buddy for Valuable info

  14. sunil kashikar said

    you can comment the line with #


    in sqlnet.ora file to resolve this issue.

    Sunil Kashikar
    Financial consultant

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