Oracle database 18c – ORA-12541: TNS:no listener

Question

I have installed Oracle 18c in my local machine and i have created a user names as

USER_NAME := c##scott
Passkey : oracle

When i used to connect to that user using cmd. The following error is populating out.

Command: sqlplus c##scott/oracle@agndev

ERROR:
ORA-12541: TNS:no listener

After checking the listener error I have rechecked my listener file

Listener File:

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = D:\ora_base)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:D:\ora_base\bin\oraclr18.dll")
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = AGNDEV))
    )
  )

Tnsnames.ora file:

# tnsnames.ora Network Configuration File: D:\ora_base\NETWORK\ADMIN\tnsnames.ora
# Generated by Oracle configuration tools.

    ORACLR_CONNECTION_DATA =
      (DESCRIPTION =
        (ADDRESS_LIST =
          (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
        )
        (CONNECT_DATA =
          (SID = CLRExtProc)
          (PRESENTATION = RO)
        )
      )

    AGNDEV =
      (DESCRIPTION =
        (ADDRESS_LIST =
          (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
        )
        (CONNECT_DATA =
          (SERVICE_NAME = AGNDEV)
        )

  )

I am new to 18c can anyone say the solution to this error.

Thank you.

Answer 1

The error message clearly says there is no listener listening on the requested address.

Check if it is running (lsnrctl status), and start it if necessary (lsnrctl start). On Windows you will need to do this in a command prompt started with administrator privileges, because it also start a Windows service. Or you can start the Windows service called something similar to OracleOraDB18Home1TNSListener.

Answer 2

You have the wrong value set for the parameter KEY in your listener.ora file. It should be EXTPROC1521 as below:

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
  )