My Oracle Support Banner

ORA-600 [OCIKDBLinkConn-8],[24327], [ORA-24327: need explicit attach before authenticating a user] (Doc ID 1277814.1)

Last updated on JANUARY 29, 2022

Applies to:

Oracle Database - Enterprise Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.


The following error is seen:

ORA-00600: internal error code, arguments: [OCIKDBLinkConn-8], [24327], [ORA-24327: need explicit attach before authenticating a user], [], [], [], [], []

The failing SQL statement is executed by an application.
The database is in and the application is using an Oracle client of version
The error happens always when there is a remote query.
Removing the PARALLEL clause of the involved table prevents the error.

This scenario can be - SQLAdvisor throws an ORA-600 [OCIKDBLinkConn-8] due to
an ORA-24327 error for statements containing an "@!" construct (which we see
here also in our SQL statement).
This construct is used internally for reverse database link operations so can
appear in SQL which has been issued to the instance across a database link
from a remote database.

Unpublished Bug 4714078 which represents the above fact has been fixed in


 The database was upgraded to
 The application and database were separated to different machines after which this error is seen. Before that it was fine.


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.