When making a request to the POST /groups/{id}/events endpoint, the Microsoft Graph API sometimes returns a status code 429 error response, indicating that too many requests have been made in too short a time period and that requests are being throttled. Based on my observations, it appears this throttling limit applies based on the intersection of the authorization token used, as well as the specific group ID specified in the request: changing either seems to bypass the throttling constraint.
However, to my surprise and in apparent contradiction to Microsoft documentation, these POST requests seem to succeed in spite of the failure response. My application utilizes change notifications to receive webhooks when new events are created in Outlook. A couple seconds after receiving the 429 error response, I receive a notification indicating the successful creation of the event sent via POST request.
Request timestamp: 2020-03-19T11:04:22.784-07:00
Webhook timestamp: 2020-03-19T11:04:24.833-07:00 (successful creation notification)
What I'm trying to figure out is, should I be expecting this behavior from all Graph APIs? Just Outlook-related? Just Group calendar-related? Just POST requests? Retrying these requests will create duplicates, so I need to know how to best handle these errors.
Going off that, any guidance to specific throttling limits for Group calendar APIs, or advice on how to avoid them, would be welcomed.