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Don Burleson Blog 







ORA-12523 Tips

Oracle Database Tips by Donald BurlesonAugust 13, 2015

I got this ORA-12523 error:


     emca -config dbcontrol db - failed with following:

SEVERE: Error Loading TransX:Listener refused the connection with the following error:

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

How do I connect this error with a fix?

Answer:  You have a listener error according to oerr for the ORA-12523 error:


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


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


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


Possible solutions:


1:  An extra bracket) in my listener.ora file

2:   Start by running "lsnrctl services" and see the status of the listener entries,


3:  Then start by testing Oracle connectivity


4:  For those with multiple listeners on non-default ports (i.e. 1521), you may get this ORA-12523 error to when creating a new database with DBCA. The solution is to to shutdown non-ASM listeners then re-run the installer.


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