ORA-03136: inbound connection timed out


Sometimes You can get ” ORA-03135: connection lost contact ” error.


Details of error are as follows.

ORA-03136: inbound connection timed out

Cause: Inbound connection was timed out by the server because user authentication was not completed within the given time specified by SQLNET.INBOUND_CONNECT_TIMEOUT or its default value
Action: 1) Check SQL*NET and RDBMS log for trace of suspicious connections.
2) Configure SQL*NET with a proper inbound connect timeout value if necessary.
TNS-12535 TNS:operation timed out
Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=
nt secondary err code: 0
Tracing not turned on.
WARNING: inbound connection timed out (ORA-3136)

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

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


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.

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