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This is quite a common problem. Here is the description:
If the Oracle client was installed using the domain administrator account instead of the local administrator, you will see such an error.
And now the solution:
1) Go to /oracle home/network/admin and open sqlnet.ora
2) Search for SQLNET.AUTHENTICATION_SERVICES= (NTS) and change it to
3) Save the file and try to connect, this should work.
If you have any questions, ask.
did you see this MOS note:
Kerberos Authentication Fails With ORA-12638 On Windows 2008 R2 (Doc ID 1225063.1)
it looks like a good match to your issue, try to add the DES ciphers:
1) Run gpedit.msc
2) Go to Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options
3) Add the DES ciphers to “Network security: Configure encryption types allowed for Kerberos”
Please note we are currently actively promoting the new support communities also, so if you want to get some
feedback from your peers as well as the attention of Oracle support engineers, please go to
This will put you in the Database Products Security community , but you can select others also from the left,
Harm ten Napel