All errors › ORA errors
ORA-12541: TNS: no listener
What it means
Nothing is listening on the host and port in the connect descriptor: listener is down, wrong port, or a firewall/container port mapping issue.
How to fix it
Start the listener (lsnrctl start), check the port (default 1521) and host, and test with tnsping or a socket check from the client machine.
Catch it before it runs
ORA Error Helper
Explains ORA-/PLS- codes inside JetBrains IDEs and DataGrip. PL/SQL Lint
Flags risky PL/SQL patterns while you type. Oracle Plan Reader
Reads execution plans and points at the slow step. PL/SQL in Practice
Kindle book with practical PL/SQL for working developers.
Explains ORA-/PLS- codes inside JetBrains IDEs and DataGrip. PL/SQL Lint
Flags risky PL/SQL patterns while you type. Oracle Plan Reader
Reads execution plans and points at the slow step. PL/SQL in Practice
Kindle book with practical PL/SQL for working developers.
Nearby errors
Updated 2026-11-12.