If the exchange appointment is successfully updated, no out is returned. To make changes to an individual occurrence within a recurring event, use the 'Exchange Appointment Find Occurrence' combined with the 'Exchange Appointment Update' handlers.For an update, the only data that needs to be entered is the Appointment ID and the Send Invitations fields.
This handle affects all occurrences of the recurring appointment.
'Send To Changed And Save Copy' is a good option when only adding attendees (just the new attendees will be notified).
The V2 handler, allows dates/times to be input in UTC or a specific time zone, with UTC being the default.
However there is then another edge case that you have to worry about.
If you have an appointment with no attendees added to it (just the organizer), then EWS may still complain and throw this error. Location = new Location // Check if the appointment has attendees other than the organizer.