ORA-12560: TNS protocol adapter error

Hi,

Sometimes You can get “ORA-12560: TNS:protocol adapter error ” error.

Details of error are as follows.

ORA-12560: TNS:protocol adapter error

To solve this error, run the relink all as follows.

$ORACLE_HOME/bin relink all

Then try to start again. It will work fine.

This error may be 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 


  TCP.INVITED_NODES=(localhost, <IP ADDRESS>)



TCP.VALIDNODE_CHECKING = YES

TCP.INVITED_NODES = (192.168.63.34,192.168.63.35,192.168.63.36)

Or Check your Oracle Home and Oracle SID if they are set correctly or not.

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

https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/