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TNS-12537: TNS:connection closed


Sometimes You can get “TNS-12537: TNS:connection closed” error.


Details of error are as follows.

TNS-12537: TNS:connection closed
Cause: “End of file” condition has been reached; partner has disconnected.
Action: None needed; this is an information message.

    TNS-12532: TNS:invalid argument
    TNS-12560: TNS:protocol adapter error
    TNS-502: Invalid argument
    32-bit Windows Error: 515: Unknown error

    Error listening on: (ADDRESS=(PROTOCOL=TCP)(Host=<hostname>)(Port=1562))
    TNS-12560: TNS:protocol adapter error 
    TNS-00584: Valid node checking configuration error

   Connecting to (ADDRESS=(PROTOCOL=TCP)(Host=hostname)(Port=1521))
   TNS-12537: TNS:connection closed
   TNS-12560: TNS:protocol adapter error
   TNS-00507: Connection closed



This error is related with the Permission or ownership or group permission, so check them if they are ok or not.

Check permission.

[oracle@msdbadm01 ~]$ ll $ORACLE_HOME/bin/oracle
-rwsr-s--x. 1 oracle oinstall 239952653 Sep 11 20:36 /u01/app/oracle/product/12.1.2/dbhome_1/bin/oracle


Revoke the user execution permission from $ORACLE/bin/oracle as follows.

[oracle@msdbadm01 ~]$  chmod 6751 $ORACLE_HOME/bin/oracle

[oracle@msdbadm01 ~]$ ll $ORACLE_HOME/bin/oracle
-rwSr-s--x. 1 oracle oinstall 239952653 Sep 11 20:36 /u01/app/oracle/product/12.1.2/dbhome_1/bin/oracle


Or the second case of this error is as follows.

There is an invalid hostname in the TCP.INVITED_NODES list in the sqlnet.ora file.

Oracle no longer  allows  the listener to startup if an invalid hostname or ip address is specified in the invited_nodes list.  The listener will not start if any of the hosts or ip addresses are note resolvable.   The only solution to this issue is to ensure that all the hostnames and ip addresses in the invited nodes list are resolvable using ping or nslookup from the host where the listener is starting.

In some cases, the localhost might cause this behavior.


To solve this error, go to sqlnet.ora and check and fix the right INVITED_NODES IP as follows,

[oracle@msdbadm01 ~]$ cd $ORACLE_HOME/network/admin
[oracle@msdbadm01 admin]$ vi sqlnet.ora 





Do you want to learn more details about RMAN, then read the following articles.


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