ORA-12541

TNS: no listener

Product: Oracle Database
Severity: Severity: critical
Updated: Oct 9, 2026
Read: 4 min

The client reached the host but nothing was listening on the target port. Either the listener is down or the client is pointing to the wrong address.

Error message

ORA-12541: TNS:no listener

Symptoms

All client connections fail immediately, without a timeout.
tnsping returns TNS-12541.
The issue began after a host reboot or network change.

Cause

The listener process is not running.
listener.ora binds to a hostname that no longer resolves to this host.
The client tnsnames.ora entry uses the wrong port.

Resolution

01
Step 1: Check listener status on the server
Run as the oracle OS user.
bash
```
lsnrctl status
```
02
Step 2: Start the listener
If status reports "no listener", start it and confirm services register within 60 seconds.
bash
```
lsnrctl start
lsnrctl services
```
03
Step 3: Verify the bind address
Confirm HOST in listener.ora resolves to a local interface, and that the port is open.
bash
```
grep -A5 LISTENER $ORACLE_HOME/network/admin/listener.ora
ss -ltnp | grep 1521
```

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