ORA-00030

This was tested on Oracle 11.2. When you run ALTER SYSTEM KILL SESSION ‘X,Y’; X must be a SID from V$SESSION and Y must be the SERIAL# from the same row. If not, you will get an ORA-00030: 

SQL> select count(*) from v$session

  2  where sid = 123

  3  and serial# = 321

  4  /

 

  COUNT(*)

----------

         0

 

SQL> alter system kill session '123,321'

  2  /

alter system kill session '123,321'

*

ERROR at line 1:

ORA-00030: User session ID does not exist.

 

SQL>