How to fix the Oracle error ORA-12523: TNS:listener could not find instance appropriate for the client connection?

In this post, you’ll learn more about the Oracle ErrorORA-12523: TNS:listener could not find instance appropriate for the client connection with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

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

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

The listener could not find any available (database) instances, that are appropriate for the client connection.

How to fix the Error ORA-12523: TNS:listener could not find instance appropriate for the client connection ?

You can fix this error in Oracle by following the below steps

Run “lsnrctl services” to ensure that the instance(s) are registered with the listener, and have status READY.