ORACLE ERROR CODE ORA-00033
ERROR
current session has empty migration password
CAUSE
An attempt was made to detach or clone the current session and it has an empty migration password. This is not allowed
ACTION
Create the session with a non-empty migration password

ORACLE ERROR CODE ORA-00032
ERROR
invalid session migration password
CAUSE
The session migration password specified in a session creation call was invalid (probably too long)
ACTION
Retry with a valid password (less than 30 chars)

ORACLE ERROR CODE ORA-00031
ERROR
session marked for kill
CAUSE
The session specified in an ALTER SYSTEM KILL SESSION command cannot be killed immediately (because it is rolling back or blocked on a network operation), but it has been marked for kill. This means it will be killed as soon as possible after its current uninterruptable operation is done
ACTION
No action is required for the session to be killed, but further executions of the ALTER SYSTEM KILL SESSION command on this session may cause the session to be killed sooner

ORACLE ERROR CODE ORA-00030
ERROR
User session ID does not exist
CAUSE
The user session ID no longer exists, probably because the session was logged out
ACTION
Use a valid session ID

ORACLE ERROR CODE ORA-00029
ERROR
session is not a user session
CAUSE
The session ID specified in an ALTER SYSTEM KILL SESSION command was not a user session (for example, recursive, etc.)
ACTION
Retry with a user session ID

ORACLE ERROR CODE ORA-00028
ERROR
your session has been killed
CAUSE
A privileged user has killed your session and you are no longer logged on to the database
ACTION
Login again if you wish to continue working