I have been using the Microsoft Exchange WebServices for a few months without any issues to read the appointments from a Public Calendar in Office 365.
Since Tuesday (August 28), the same code without any modifications (the very same build) is now triggering an "Expected an item Id but received a folder Id.
" exception. It ran fine on Monday.
I found out that my error is happening on this specific instruction:
FindItemsResults<Appointment> lstAppointments = ((CalendarFolder) objFindFoldersCalendar.Folders).FindAppointments(objCalendarView);
Is somebody is aware of anything changed in Office 365 regarding public folders (I can read regular calendar without issues).
It is mostly the same code found at https://www.emoreau.com/Entries/Articles/2018/05/A-Net-application-to-extract-appointments-from-Office-365-public-calendars.aspx