Toad World® Forums

ORA-12541: TNS:no listener


#1

I have installed Toad for Oracle 64bit and Oracle instant-client basic for 64 bit PC on Windows 8 64bit system. After setting all paths and required system variable in the ‘Environment Variable’ for the PC, I am still getting error. The error prompt I am getting is as follows:

ORA-12541: TNS:no listener

Items Checked

TNS_ADMIN environment variable is defined as “C:\instantclient_12_1”

“C:\instantclient_12_1\tnsnames.ora” was located

The following connect descriptor was found for ORATST in the tnsnames.ora file

ORATST=
(DESCRIPTION=
(ADDRESS=
(PROTOCOL=TCP)
(HOST=127.0.0.1)
(PORT=1521)
)
(CONNECT_DATA=
(SERVICE_NAME=oratst)
)
)

“C:\instantclient_12_1\sqlnet.ora” was located

NAMES.DIRECTORY_PATH specifies TNSNAMES in the sqlnet.ora file

Steps to Take

Verify that the port specified in the connect descriptor is correct in the tnsnames.ora file
Verify that the listener is running and that it is properly configured


#2

Could you check as well firewall settings (Windows defender or your dedicated antivirus program) as well.


#3

Step-1: First check your listener status.

lsnrctl status

Check the status of your listener.

Step-2: Start the listener, if listener is not running.

lsnrctl start listenername;

This command will start all your listener services.

Step-3: Stop the listener, if listener is running.

lsnrctl stop

This command will stop all your listener services.

Step-4: Restart the listener.

lsnrctl reload

This command will restart all your listener services.