ORA-12547: TNS:lost contact Error

When I connect to Oracle database, I got ” ORA-12547: TNS:lost contact ” error.

 

 

ORA-12547: TNS:lost contact

 

Details of error are like following.

[[email protected] ~]$ sqlplus mehmet/[email protected]

SQL*Plus: Release 12.1.0.2.0 Production on Thu Aug 1 16:16:23 2019

Copyright (c) 1982, 2014, Oracle. All rights reserved.

ERROR:
ORA-12547: TNS:lost contact


Enter user-name: ^C
[[email protected] ~]$


TNS:lost contact

This ORA-12547: TNS:lost contact error is related with the tcp.validnode_checking = yes in sqlnet.ora file.

 

To solve this problem, firstly check sqlnet.ora file.

[[email protected] PRELIVE_MehmetSalih]$ cat sqlnet.ora
###############################################################
#
# Do not edit settings in this file manually. They are managed
# automatically and will be overwritten when AutoConfig runs.
# For more information about AutoConfig, refer to the Oracle
# E-Business Suite Setup Guide.
#
#$Header: NetServiceHandler.java 120.28.12020000.2 2012/07/05 11:52:15 brayasam ship $
#
###############################################################

NAMES.DIRECTORY_PATH=(TNSNAMES, ONAMES, HOSTNAME)
SQLNET.EXPIRE_TIME= 10
tcp.validnode_checking = yes
tcp.invited_nodes=(MehmetSalih.Deveci.local)
SQLNET.INBOUND_CONNECT_TIMEOUT =60


IFILE=/data/oracle/PRELIVE/12.1.0/network/admin/PRELIVE_MehmetSalih/sqlnet_ifile.ora
[[email protected] PRELIVE_MehmetSalih]$

 

 

 

You should remove tcp.validnode_checking = yes and tcp.invited_nodes=(MehmetSalih.Deveci.local) entries.

[[email protected] PRELIVE_MehmetSalih]$ vi sqlnet.ora
[[email protected] PRELIVE_MehmetSalih]$
[[email protected] PRELIVE_MehmetSalih]$



After remove related parameters, sqlnet.ora file should be like following.


[[email protected] PRELIVE_MehmetSalih]$ cat sqlnet.ora
###############################################################
#
# Do not edit settings in this file manually. They are managed
# automatically and will be overwritten when AutoConfig runs.
# For more information about AutoConfig, refer to the Oracle
# E-Business Suite Setup Guide.
#
#$Header: NetServiceHandler.java 120.28.12020000.2 2012/07/05 11:52:15 brayasam ship $
#
###############################################################

NAMES.DIRECTORY_PATH=(TNSNAMES, ONAMES, HOSTNAME)
SQLNET.EXPIRE_TIME= 10
SQLNET.INBOUND_CONNECT_TIMEOUT =60


IFILE=/data/oracle/PRELIVE/12.1.0/network/admin/PRELIVE_MehmetSalih/sqlnet_ifile.ora
[[email protected] PRELIVE_MehmetSalih]$

 

ORA-12547

To solve this error, Now reload or stop start Listener. Login database via sqlplus or Toad like following.

 

Problem has been solved.

[[email protected] ~]$ sqlplus mehmet/[email protected]

SQL*Plus: Release 12.1.0.2.0 Production on Thu Aug 1 16:33:34 2019

Copyright (c) 1982, 2014, Oracle. All rights reserved.

Last Successful login time: Thu Aug 01 2019 17:24:06 +03:00

Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

 

 

 

Sometimes oracle.exe or oracle executable file’s permission may be modified

Check oracle like following.

[orac[email protected] ~]$ cd $ORACLE_HOME/bin
[[email protected] bin] $ ls -ltr oracle
[[email protected] bin] $ -rwx-xr-x 1 oracle oinstall 136803483 Jul 16 10:24 oracle

 

Change permissions and give 6751 permission as below:

[[email protected] bin] $ chmod 6751 oracle
[[email protected] bin] $ ls -ltr oracle
-rwsr-s--x 1 oracle oinstall 136803483 Jul 16 10:24 oracle

 

Other case I have seen that extra slash usage with Oracle home as follows 🙂

/u01/app/oracle/product/18.0/dbhome_1/

 

To solve this problem check your Oracle home’s extra slash and remove it 😉 use as follows without slash.

/u01/app/oracle/product/18.0/dbhome_1

 

 

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

Oracle Database Tutorials for Beginners ( Junior Oracle DBA )

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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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