WARNING: Subscription for node down event still pending in Listener log

In the listener log file you constantly get the following warning message.

WARNING: Subscription for node down event still pending.

The warning messages are related to the Oracle TNS Listener's default subscription to the Oracle Notification  Service (ONS). This subscription to ONS is introduced in Oracle 10g for RAC environment. Listener subscription to ONS is useful to use advanced features like Fast Application Notification events(FAN) , Fast Application Fail over (FAF) and Fast Connection Failover (FCN) in RAC. So in a non-RAC environment subscription to ONS is not needed. So in a standalone system we can disable it and thus avoid warning message.



Solve the WARNING message in the listener log.
Disable subscription for listener to ONS. This can be done by setting the following parameter in the listener.ora.

SUBSCRIBE_FOR_NODE_DOWN_EVENT_{listener_name}=OFF

Where {listener_name} should be replaced with the actual listener name configured in the LISTENER.ORA file.

After that you need to stop and start the listener by,

lsnrctl stop
lsnrctl start

Alternatively you can reload the listener if availability is important to you. Do it just by,

lsnrctl reload

This will prevent the messages from being written to the log file.