Hi,

I got ” The Network Adapter could not establish the connection” error in SQL Developer, TOAD and PL/SQL Developer connection for Oracle database.

The Network Adapter could not establish the connection

Details of error are as follows.

java.sql.SQLException: Io exception: The Network Adapter could not establish the connection.

The Network Adapter could not establish the connection error is related with the wrong URL or IP Adress, Service_Name, SID and Port number.

If you got The Network Adapter could not establish the connection error, then check your URL, IP Adress, Port,Service_Name, SID and DNS, If any of them is wrong, then fix it.

If your URL, IP Adress, Port, Service_Name or SID are correct, then check your database listener if it is configured properly or not.

lsnrctl status | lsnrctl stop | lsnrctl start

To solve The Network Adapter could not establish the connection error, type your URL, IP Adress, Port,Service_Name, SID or reload and stop, start your database’s listener as follows.

[oracle@MSDBdbadm01 ~]$ lsnrctl status

LSNRCTL for Linux: Version 12.1.0.2.0 - Production on 17-SEP-2020 15:54:45

Copyright (c) 1991, 2014, Oracle. All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 12.1.0.2.0 - Production
Start Date 23-JUL-2020 01:45:30
Uptime 56 days 14 hr. 9 min. 15 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /u01/app/12.1.0.2/grid/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/MSDBdbadm01/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.3.16)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.9)(PORT=1521)))
Services Summary...
Service "+ASM" has 1 instance(s).
Instance "+ASM1", status READY, has 1 handler(s) for this service...
Service "-MGMTDBXDB" has 1 instance(s).
Instance "-MGMTDB", status READY, has 1 handler(s) for this service...
Service "MSDB" has 1 instance(s).
Instance "MSDB1", status READY, has 1 handler(s) for this service...
Service "MSDBXDB" has 1 instance(s).
Instance "MSDB1", status READY, has 1 handler(s) for this service...
Service "_mgmtdb" has 1 instance(s).
Instance "-MGMTDB", status READY, has 1 handler(s) for this service...
Service "cluster_clu1" has 1 instance(s).
Instance "-MGMTDB", status READY, has 1 handler(s) for this service...
The command completed successfully
[oracle@MSDBdbadm01 ~]$




[oracle@MSDBdbadm01 ~]$ lsnrctl stop

[oracle@MSDBdbadm01 ~]$ lsrnctl start

You should use IP, Port, Service_name as above.

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