Oracle client ORA-12541: TNS:no listener

Question

I am new on Oracle database, but I have one issue. On my Database server (server1) listener and database instance run correctly and I can use sqlplus to connect to this DB. When I connect to database by using other server, I check the TNS configuration and it is correct but system says:

ERROR:
ORA-12541: TNS:no listener

My database is Oracle 10gR2

So how can I solve this issue?

Answer 1

You need to set oracle to listen on all ip addresses (by default, it listens only to localhost connections.)

Step 1 - Edit listener.ora

This file is located in:

• Windows: %ORACLE_HOME%\network\admin\listener.ora.
• Linux: $ORACLE_HOME/network/admin/listener.ora

Replace localhost with 0.0.0.0

# ...

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 0.0.0.0)(PORT = 1521))
    )
  )

# ...

Step 2 - Restart Oracle services

• Windows: WinKey + r

  services.msc
  

• Linux (CentOs):

  sudo systemctl restart oracle-xe