ORA-12541
- host_port: The host and port that the Oracle Database listener process is on.
Cause
The connection request could not be completed because either the database listener process was not running on the specified host and port, or an Interprocess Communication (IPC) protocol connection was attempted but there was no listener for the specified key running on the local machine. PL/SQL applications using UTL packages can also get this error if the external server process is not listening on the specified address.
Action
If the error shows the host and port that the connection tried to use, then ensure that a listener process is running on that host and is listening on that port. If the message indicates that there was no listener at the specified key, then ensure that the listener is running on the local machine and listening for the specified key. The listener process is used to initially handle all connections to Oracle Database.
- Check for mistakes in the specified connection string.
- If you are using an alias from a tnsnames.ora file, then verify the correctness of the host and port. Alternatively, verify the correctness of the key if you are using an IPC connection.
- If using an Easy Connect connection string, then ensure that the host and port are correct.
- Use lsnrctl to check that the listener is running and to verify the port or key it listens to. Run one of the following:
- lsnrctl status
- Or, when a listener is named in the listener.ora file, run: lsnrctl status <listener_name>
- Or, if an Oracle Connection Manager (Oracle CMAN) proxy listener is named in the cman.ora file, run: cmctl show status -c <cman_name>