| ERROR | 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 - 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. |