ORA-12502: TNS:LISTENER RECEIVED NO CONNECT_DATA FROM CLIENT

Error:

When clients attempt to connect to the database, they can not connect with the error “ORA-12502: TNS: listener received no CONNECT_DATA from the client”.

Now we will try to find out both the causes and how to solve this problem.

Reason:

Missing host definition in the local_listener parameter.

Solution:

The definition in the local_listener parameter should be changed as follows.

Missing Host Definition:

Correct Host Definition:

If the database is RAC, the definition of sid = ‘XX’ should also be added.