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Listener Does Not Create Handlers for Started Services With Multiple Endpoint Registration (ORA-12520, ORA-12516) (Doc ID 1504785.1)

Last updated on FEBRUARY 03, 2022

Applies to:

Advanced Networking Option - Version and later
Information in this document applies to any platform.


When an instance registers with multiple endpoints on the same listener, at service startup or relocation, the listener will create the service but zero handlers.

The reported errors are:

ORA-12520: TNS:listener could not find available handler for requested type of server
ORA-12516 TNS:listener could not find instance with matching protocol stack

Checking the listener services using lsnrctl status <listener name>, one can notice the 0 handlers being created for the service:

Service "" has 1 instance(s).
 Instance "TEST", status READY, has 0 handler(s) for this service...





This situation appears when adding multiple endpoints to the same listener. The local_listener is automatically set by the clusterware (or even manually) to register to all listener endpoints. When this happens, this issue is hit.
It is a very common scenario when using SSL registration, because the listener is often configured to listen to both TCP and TCPS endpoints.



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