ORA-12523 Errors Connecting After Upgrading A Second Database To 11gr2 (Doc ID 1368744.1)

Last updated on APRIL 13, 2017

Applies to:

Oracle Net Services - Version: 11.2.0.2 and later   [Release: 11.2 and later ]
Information in this document applies to any platform.

Symptoms


After upgrading a second database instance from 10gR2 to 11gR2 (11.2.0.2) on the same machine, unable to connect to the original 11gR2 database instance that was previously working fine.

Errors received:

ORA-12523: TNS:listener could not find instance appropriate for the client after 11g upgrade

Cause

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