Oracle Error Message
ORA-00031: session marked for kill
Reason for the Error
The session defined in an ALTER SYSTEM KILL SESSION command has been marked for kill even though it cannot be terminated right now (because it is rolling back or blocked on a network operation).
This signifies that as soon as its current unabruptable operation is complete, it will be put to death.
Solution
The session can be terminated without additional action, but subsequent uses of the ALTER SYSTEM KILL SESSION command on this session could hasten its demise.