Cause: An attempt was made to use ALTER SYSTEM KILL SESSION to kill the
current session.
Action: If it is necessary to kill the current session, do so from another session.
ORA-00027 comes under "Oracle Database Server Messages".
These messages are generated by the Oracle database server when running any Oracle program.
How to kill session:
1. identify which session to kill using following query:
select
s.sid,
s.serial#,
spid,
trim(s.machine) machine,
trim(s.module) module,
status
from
v$session s,
v$process p
where
paddr=addr
and module is not null
order by 1,2
2. Killing a session
ALTER SYSTEM KILL SESSION 'sid,serial#';
or you can kill at OS level on linux using
kill -9 spid