On 12.2, ORA-603 ORA-20 is Raised Even When Maximum Number of Processes Has Not Exceeded

On 12.2.0.1, connecting to a new session may result in ORA-603, ORA-20 even when the PROCESSES resource limit has not been reached.

This document describes this new behavior on 12.2.

> sqlplus system/manager

SQL*Plus: Release 12.2.0.1.0 Production on Fri Oct 20 01:15:50 2017

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ERROR:
ORA-00603: ORACLE server session terminated by fatal error
ORA-00020: maximum number of processes () exceeded
Process ID: 0
Session ID: 0 Serial number: 0

SOLUTION

Starting with 12.2.0.1, small number of processes are reserved for local SYSDBA user connection.

By default, this number is 2, and ORA-603, ORA-20 will be thrown when the number of processes generated after non-sysdba user's connection reaches PROCESSES - 2.

If it is necessary to revert back to pre-12.2 behavior, set hidden parameter _min_sys_process=0 and restart the database.

alter system set "_min_sys_process"=0 scope=spfile;
shutdown immediate;
startup;