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ORA-12523 Connecting Via the Listener (Doc ID 2313136.1)

Last updated on FEBRUARY 10, 2023

Applies to:

Oracle Net Services - Version to [Release 12.1 to 12.2]
Oracle Database - Standard Edition - Version to [Release 12.1]
Oracle Database - Enterprise Edition - Version to [Release 11.2]
Microsoft Windows x64 (64-bit)


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.




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


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