500 error response when updating calendar event via graph API

Question

On behalf of one specific customer, we've suddenly started getting a 500 response when attempting to make PATCH requests to the /v1.0/me/calendars/{calendar_id}/events/{event_id} endpoint in order to update certain calendar events.

The error response does not explain in detail what the issue is. It appears to be a generic 500 response:

500: Internal Server Error
Body: {'error': {'code': 'ErrorInternalServerError', 'message': 'An internal server error occurred. The operation failed.'}}
Headers: {'Cache-Control': 'private', 'Transfer-Encoding': 'chunked', 'Content-Type': 'application/json; odata.metadata=minimal; odata.streaming=true; IEEE754Compatible=false; charset=utf-8', 'Content-Encoding': 'gzip', 'Vary': 'Accept-Encoding', 'Strict-Transport-Security': 'max-age=31536000', 'request-id': '93a9e8ae-17b3-4835-b43a-12a4d10ed243', 'client-request-id': '93a9e8ae-17b3-4835-b43a-12a4d10ed243', 'x-ms-ags-diagnostic': '{"ServerInfo":{"DataCenter":"East US","Slice":"E","Ring":"5","ScaleUnit":"008","RoleInstance":"BL02EPF00027348"}}', 'Date': 'Tue, 09 Jul 2024 15:06:11 GMT'}

We are wondering what actually is going wrong here so that we can remedy the issue, or whether this is something that's going wrong within Microsoft's system.