ERROR ORA-00020 maximum number of processes (%s) exceeded

Issue:

Error when connecting the database using $sqlplus / ' as sysdba' 

ERROR ORA-00020 maximum number of processes (%s) exceeded

Fix:

Step-1

Restart the server and Edit init.ora file to increase the number of processes.

or 

Connect to sqlplus with sysdba

#sqlplus / ' as sysdba'
$show parameter;
or
$show parameter process;

Step-2

$ALTER SESSION SET processes = 2000 (your value);

Cause:  An operation requested a resource that was unavailable.

            The maximum number of processes is specified by the initialization

             parameter PROCESSES.

            When this maximum is reached, no more requests are processed.

Action: Try the operation again in a few minutes.

            If this message occurs often, shut down Oracle, increase the PROCESSES

            parameter in the initialization parameter file, and restart Oracle.