Error code
Oracle ORA-12541
ORACLEORA-12541
Database Error Code· An error code returned by a database server such as PostgreSQL or MySQL.
What it means
TNS no listener — connection refused because nothing is listening on the port.
How to fix it
- Start the Oracle listener with lsnrctl start.
- Verify the listener port (default 1521) is open and not blocked by a firewall or security group.
- Confirm the host and port in the connection string are correct for the target database.
Not affiliated with Oracle. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.
More Oracle codes
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