When i am trying to connect to one of our databases on Toad/SQL developer/SQLPLUS, getting the issue that the ORA-12541 TNS No Listener.
steps to take:
verify that the port specified in the connect descriptor is correct in tnsnames.ora
verify that the tns listener is running and that is properly configured.
please check this issue, unable to know what to do.
The listener is like the doorman at a hotel. The hotel (the database) might be there, and open for business, but if the doorman isn't there, then you can't get in.
From a command prompt do:
tnsping XYZ
for example
C:\oracle\product\grid\bin>tnsping db122
TNS Ping Utility for 64-bit Windows: Version 12.2.0.1.0 - Production on 23-SEP-2017 12:25:38
Copyright (c) 1997, 2016, Oracle. All rights reserved.
Used parameter files:
C:\oracle\product\12.2.0.1\network\admin\sqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = db122)))
OK (20 msec)
This will tell you the host name and port number. You then need to make sure that there is a listener running *on the database host* that matches the above,
C:\oracle\product\grid\bin>lsnrctl status
LSNRCTL for 64-bit Windows: Version 12.2.0.1.0 - Production on 23-SEP-2017 12:26:24
Copyright (c) 1991, 2016, Oracle. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for 64-bit Windows: Version 12.2.0.1.0 - Production
Start Date 13-SEP-2017 22:38:09
Uptime 9 days 13 hr. 48 min. 14 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File C:\oracle\product\12.2.0.1\network\admin\listener.ora
Listener Log File c:\oracle\diag\tnslsnr\xps13\listener\alert\log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=xps13)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Services Summary...
Service "+ASM" has 1 instance(s).
Instance "+asm", status READY, has 1 handler(s) for this service...
Service "+ASM_DATA" has 1 instance(s).
Instance "+asm", status READY, has 1 handler(s) for this service...
Service "db122" has 1 instance(s).
Instance "db122", status READY, has 1 handler(s) for this service...
Service "db122XDB" has 1 instance(s).
Instance "db122", status READY, has 1 handler(s) for this service...
The command completed successfully