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

(Doc ID 1504785.1)

Last updated on FEBRUARY 17, 2017

Applies to:

Advanced Networking Option - Version and later
Information in this document applies to any platform.
Checked for relevance on 14-APR-2014


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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