I am trying to create an event on a Conflunence calendar using an admin account. When using my own account ID for the "person" field, the event is created successfully. However, any other account ID results in an "Invalid user" error. This occurs on all calendars, even those without any restrictions on them. This also occurs across multiple spaces. I added an event for the user in the UI and then tried to use the API again, but the same result occurred. All user IDs were obtained from the /wiki/rest/api/user endpoint. Below is the payload used. Any ideas as to why only one account ID works?
PUT request
http://domain.atlassian.net/wiki/rest/calendar-services/1.0/calendar/events.json
Auth - Basic Auth
Header - Content-Type: application/x-www-form-urlencoded
{
"subCalendarId": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
"eventType": "event",
"what": "Test event",
"person": "123456:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
"startDate": "November 24, 2025",
"allDayEvent": "false",
"startTime": "2:00 PM",
"endTime": "10:00 AM",
"endDate": "November 25, 2025",
"userTimeZoneId": "America/New_York"
}
