Fixed – ORA-12518: TNS:listener could not hand off client connection

You tried to connect with Oracle Database and got "ORA-12518 listener could not hand off client connection" error. Now what action will you take to get rid of this error? Here is the answer:

Error Message:

ORA-12518: TNS: listener could not hand off client connection.

Solution-1:

First check your database whether it is in start or stop mode.

SQL> shutdown immediate;

SQL> Startup;

Solution-2:

You have to increase PROCESSES initialization parameter in Oracle database. To check the existing value of the PROCESSES issue following command.

SQL> show parameter processes

As we have already started our database normally or using spfile, then run following command to alter system processes to 450.

SQL> alter system set processes=450 scope=spfile;

If you have started your database using pfile, process parameter must be set in pfile.

Solution-3:

If you are getting ORA-12518 because of a shared server issue, you can shutdown the dispatcher with below command.

SQL> alter system shutdown immediate 'D001';
Then add on new dispatchers.

SQL> alter system set DISPATCHERS = '(protocol=tcp)(dispatchers=3)';

Resolving ORA-12518 requires you to evaluate the syntax depending on your dispatcher value in the Spfile.ora or init.ora files.  When you increase DISPATCERS to resolve ORA-12518 you should also keep an eye on the shared server ratio.