ORA-12638: Credential retrieval failed

Question

I have a legacy VB6 application which I\'ve inherited. The issue I\'m facing is that I\'m getting the infamous

ORA-12638: Credential retrieval failed
         


        

Answer 1

Know it's an old question but it has started appearing with the recent Windows update. The way to easily solve it is to set

SQLNET.AUTHENTICATION_SERVICES= (NONE)

in the sqlnet.ora.

Answer 2

I installed Oracle Database 11g Express Edition 32-bit on Windows 10 professional 64-bit (spanish edition).

After restart PC all works ok.
But the next day I get error using SQL*PLus and SQLTools 1.9 build 15:

 ORA-12638: Credential retrieval failed

I modified the sqlnet.ora file so:

SQLNET.AUTHENTICATION_SERVICES= (NONE)

and now I can connect using SQLPlus, SQLTools 1.9 build 15.

Answer 3

Honestly this is one of those errors that can be caused by lots of different root problems.

On the assumption your database server is Windows, check its event log, both System and Application. You may find something there that is useful.

I have encountered this error in some cases because the account under which the Oracle service was running got locked.

I have also encountered it in cases where we never found the explanation, but we were always able to clear up the issue by having the user lock and unlock their PC.

Is the VB application running on a different machine than the client that can connect? If so, is it possible to test using a different client program on the same machine -- or is it possible to try the VB application on your machine?

Answer 4

I know this is a very old post but I have found a solution that has worked for me (Legacy VB6 Application):

Change the following entry in the sqlnet.ora file:

Original Entry - SQLNET.AUTHENTICATION_SERVICES= (NTS)

Modified Entry - SQLNET.AUTHENTICATION_SERVICES= (NONE)

Here is a LINK to the solution

Answer 5

If you are running a web app under IIS, restarting IIS seem to help. But this is one sucker of an issue that has not much reasoning behind.