ORA-12521: TNS listener does not currently know of instance requested in connect descriptor

Hi,

Sometimes You can get “ORA-12521: TNS:listener does not currently know of instance requested in connect descriptor ” error.

 

Details of error are as follows.

ORA-12521: TNS:listener does not currently know of instance requested in connect descriptor
Cause: The listener received a request to establish a connection to a database or other service.
The connect descriptor received by the listener specified in addition to the service name an instance
name for an instance (usually a database instance) that either has not yet dynamically registered with
the listener or has not been statically configured for the listener. This may be a temporary condition
such as after the listener has started, but before the database instance has registered with the listener.

Action:– Wait a moment and try to connect a second time.

– Check which instances are currently known by the listener by executing: lsnrctl services <listener name>

– Check that the INSTANCE_NAME parameter in the connect descriptor specifies an instance name known by the listener.

– Check for an event in the listener.log file.

 

 

 

This error is related with the listener and registered services of database. Check listener status

$ lsnrctl status listener

Listener should be always started.

 

Check listener services which services are listening.

lsnrctl services <listener name>

 

Check the SID parameter known by the listener. If the right SID specified or not in the listener status.

 

If the related service name and instance don’t exist in the listener status, then set it in the database and register it to database as follows.

 

SQL> alter system set local_listener='(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.63.34)(PORT=1521)))' scope=both;

SQL> alter system register;

Or

– Wait a moment and try to connect a second time.

– Check which instances are currently known by the listener by executing: lsnrctl services <listener name>

– Check that the INSTANCE_NAME parameter in the connect descriptor specifies an instance name known by the listener.

– Check for an event in the listener.log file.

 

 

Do you want to learn more details about RMAN, then read the following articles.

https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/

 

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About Mehmet Salih Deveci

I am Founder of SysDBASoft IT and IT Tutorial and Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress [email protected].-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  [email protected] a mail atabilirsiniz.

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