ORA-12547: TNS:lost contact error and How to Solve ORA-12547 Error

Hi,

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

Details of error are like following.

[oracle@MehmetSalih ~]$ sqlplus mehmet/mehmet@PRELIVE

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
[oracle@MehmetSalih ~]$

 

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

[oracle@MehmetSalih 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
[oracle@MehmetSalih PRELIVE_MehmetSalih]$

 

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

[oracle@MehmetSalih PRELIVE_MehmetSalih]$ vi sqlnet.ora
[oracle@MehmetSalih PRELIVE_MehmetSalih]$
[oracle@MehmetSalih PRELIVE_MehmetSalih]$



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


[oracle@MehmetSalih 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
[oracle@MehmetSalih PRELIVE_MehmetSalih]$

 

Now reload or stop start Listener. Login database via sqlplus or Toad like following.

 

Problem has been solved.

[oracle@MehmetSalih ~]$ sqlplus mehmet/mehmet@PRELIVE

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.

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

 

Change permissions and give 6751 permission as below:

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

Mehmet Salih Deveci

I am Founder of 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 mehmetsalih.deveci@outlook.com.-                                                                                                                                                                                                                                                 -Oracle DBA, SQL Server DBA, APPS DBA,  Exadata, Goldengate, EBS ve linux Danışmanlık ve Eğitim için  mehmetsalih.deveci@outlook.com a mail atabilirsiniz.

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