Wednesday, January 1, 2020

How to resolve ORA-12516 TNS:listener could not find available handler with matching protocol stack?

We see the error related to Listener refused the connection with following other error message as below:

ORA-12516,TNS:listener could not find available handler with matching protocol stack.
or 
Status:Failure -Test failed:IO Error: Got minus one from read call.

Usually we face the above error when number of process is not sufficient in the initialization parameter file to create additional connections.

Resolution:

Check the current process limit in V$parameter view

Connect to the correct DB or PDB if you are running 12c or above if it is a pluggable DB;

1. Alter system set processes=<new limit> scope=spfile;

2. Bounce the DB or PDB.

3. Restart the listener services.