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: and later   [Release: 11.2 and later ]
Information in this document applies to any platform.


After upgrading a second database instance from 10gR2 to 11gR2 ( 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


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