Oracle error
ORA-12541
ORA-12541: TNS:no listener
What usually causes it
Nothing is listening on that host and port.
What to check first
Start the listener (lsnrctl start, or srvctl start listener on Grid Infrastructure) and confirm the host and port in the connect string.
Scripts that help
- Listener status and services (lsnrctl)What the listener is doing and which services it knows about, from the database server. Then test the path from a client machine. Pairs with Listener…
- Cluster status commands (srvctl and crsctl)The Clusterware commands for checking a RAC database, its services and every cluster resource.
Tool
- Connection string builderEZConnect, tnsnames.ora, JDBC, psql, sqlcmd and more