ORA-12535: TNS operation timed out

Sometimes You can get “ORA-12535: TNS:operation timed out ” error.


ORA-12535: TNS operation timed out

Details of error are as follows.

ORA-12535: TNS:operation timed out

Cause: The requested operation could not be completed within the time out period.

Action: Look at the documentation on the secondary errors for possible remedy. See SQLNET.LOG to find secondary error if not provided explicitly. Turn on tracing to gather more information.

[oracle@msdbadm01 admin]$ tnsping MSDB

TNS Ping Utility for Linux: Version - Production on 06-MAY-2020 13:02:57

Copyright (c) 1997, 2013, Oracle. All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias
TNS-12535: TNS:operation timed out
[oracle@msdbadm01 admin]$





This ORA-12535 error is related with firewall or listener timeout.


If firewall is open, then disable it as follows.

service iptables stop
chkconfig iptables off

service ip6tables stop
chkconfig ip6tables off

You can disable firewall in Redhat with below script.

systemctl stop firewalld
systemctl disable firewalld



TNS operation timed out

Or Check your IP Adress, Port if they are incorrect, you can get this error. To solve this error, fix IP adress and port.



TNS-12535 and ORA-03135: connection lost contact error are related with the Network traffic and High loaded database operations.

To solve this error, add the following parameter to the SQLNET.ORA file ( under $ORACLE_HOME/network/admin/ ).




then restart the Listener as follows.

$ srvctl stop listener
$ srvctl start listener



$ lsnrctl stop listener

$ lsnrctl start listener


Or Check database server if it is up or not.


Do you want to learn Oracle Database for Beginners, then Click and read the following articles.

Oracle Database Tutorials for Beginners ( Junior Oracle DBA )

About Mehmet Salih Deveci

I am Founder of SysDBASoft IT and IT Tutorial and Certified Expert about Oracle & SQL Server database, Goldengate, Exadata Machine, Oracle Database Appliance administrator with 10+years experience.I have OCA, OCP, OCE RAC Expert Certificates I have worked 100+ Banking, Insurance, Finance, Telco and etc. clients as a Consultant, Insource or Outsource.I have done 200+ Operations in this clients such as Exadata Installation & PoC & Migration & Upgrade, Oracle & SQL Server Database Upgrade, Oracle RAC Installation, SQL Server AlwaysOn Installation, Database Migration, Disaster Recovery, Backup Restore, Performance Tuning, Periodic Healthchecks.I have done 2000+ Table replication with Goldengate or SQL Server Replication tool for DWH Databases in many clients.If you need Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS Consultancy and Training you can send my email adress [email protected].-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  [email protected] a mail atabilirsiniz.


  1. I have checked all the above mentioned parameters, but it doesn’t resolve my issue…..still showing operation timed out. 🙁

  2. Very much helpful for me.

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