TNS-12547: TNS:lost contact , Linux Error: 104: Connection reset by peer

TNS-12547: TNS:lost contact

TNS-12560: TNS:protocol adapter error

TNS-00517: Lost contact

Linux Error: 104: Connection reset by peer

or

TNS-12537: TNS:connection closed

TNS-12560: TNS:proto adapter error

TNS-00507: Connection closed

Linux Error: 29: Illegal seek

Solution:

Make sure the following loop back entries exist in /etc/hosts file. If the Operating system configured with IPV6 then you need to add second line as well. Start the listener after adding the following entries. For more information please check Doc ID 960152.1 from Oracle Support.

127.0.0.1 localhost.localdomain localhost

::1 localhost6.localdomain localhost6