Exception thrown if attempting to create a new {@code Subject}{@link org.apache.shiro.subject.Subject#getSession() session}, but that {@code Subject}'s sessions are disabled.
Note that this exception represents an invalid API usage scenario - where Shiro has been configured to disable sessions for a particular subject, but a developer is attempting to use that Subject's session.
In other words, if this exception is encountered, it should be resolved by a configuration change for Shiro and
not by checking every Subject to see if they are enabled or not (which would likely introduce very ugly/paranoid code checks everywhere a session is needed). This is why there is no {@code subject.isSessionEnabled()} method.
@since 1.2