ORA-12523 Connecting Via the Listener

(Doc ID 2313136.1)

Last updated on OCTOBER 20, 2017

Applies to:

Oracle Net Services - Version 12.1.0.2 and later
Microsoft Windows x64 (64-bit)

Symptoms

In an environment where multiple databases are registered against a single listener.
Some connections via the listener fail with the following error:

 

ORA-12523: TNS:listener could not find instance appropriate for the client

 

In this case, the LOCAL_LISTENER setting for each instance might be specified differently.
One instance shows the HOST field populated with a hostname.
Another instance shows the HOST field populated by an ip address.

 

 

Changes

 This is likely a new installation or a database has recently been created on this server.

Cause

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