Make sure you're providing the UPN value for the room mailbox, it can differ from the email address. If running in the delegate permissions model, make sure you have at least Calendars.Read.Shared permissions granted on the app, and Full Access permissions on the room calendar.
ErrorItemNotFound https://graph.microsoft.com/v1.0/users/room1@gaiadigits.com/calendar/events
Kevin Xiong
21
Reputation points
I'm not sure I'm doing the right thing, am I? I wanted to get a calendar event for a conference room and requested the interface; it returned some error messages and after checking many community answers I didn't find a solution.
https://graph.microsoft.com/v1.0/users/room1@gaiadigits.com/calendar/events