Google_Service_Exception thrown

Error calling GET https://www.googleapis.com/calendar/v3/calendars/mccoolpi3%40gmail.com/events/59jg78u0g62c0mituu2oimt50o?key=AIzaSyCupIRMQmH_LtNl_nQfw_BSNVW9kNtWkhl: (404) Not Found