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Sqlplus Connection Fails with ORA-12638 (Doc ID 782419.1)

Last updated on OCTOBER 30, 2020

Applies to:

Advanced Networking Option - Version and later
z*OBSOLETE: Microsoft Windows
Checked for relevance on 23-Sep-2012



You are using Operating System authentication like NTS or Kerberos. While connecting to the database from sqlplus it fails with the ORA-12638.

You may connect with the following syntax

For local SYS connections,
sqlplus / as sysdba

For User connections,
sqlplus /@<alias>


sqlnet client trace shows the below SSPI error:

[26-NOV-2008 05:43:31:353] naun5authent: driver state is 2
[26-NOV-2008 05:43:31:353] nacomrp: entry
[26-NOV-2008 05:43:31:353] nacomrp: exit
[26-NOV-2008 05:43:31:353] nacomrp: entry
[26-NOV-2008 05:43:31:353] nacomrp: exit
[26-NOV 2008 05:43:31:353] naun5authent: SSPI: 0x8009030c error in InitializeSecurityContext
[26-NOV-2008 05:43:31:353] naun5authent: exit
[26-NOV-2008 05:43:31:353] naunauthent: exit
[26-NOV-2008 05:43:31:353] nau_ccn: get credentials function failed
[26-NOV-2008 05:43:31:353] nau_ccn: failed with error 12638


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