ORA-01012: not logged on

The following happened when a user connects to an already running database: $ sqlplus / as sysdba SQL*Plus: Release 11.2.0.3.0 Production on Wed Apr 1 08:13:58 2015 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected. SQL> SQL> SQL> SQL> select name from v$database; select name from v$database * ERROR at line 1: ORA-01012: not logged on Process ID: 0 Session ID: 0 Serial number: 0 Cause: This is usually happens to an heavily loaded database. Solution: The following options will help resolve the challenge. 1. Kill Oracle processes> #ps -ef |grep ora_smon* #kill -9 smon_process_id $sqlplus / as sysdba SQL> startup 2. Restart the database server and bring up the database afterwards. 3. Stop the application server and stop listener to prevent new incoming connections. This will release sessions and allow new connections to the database. Additionally, it is advised that the "processes" parameter be increased on the database. SQL> show parameter processes SQL> alter system set processes=new_value scope spfile; SQL> shutdown (immediate) SQL> startup SQL> show parameter processes