Some Office 365 accounts may be required to re-authenticate due to a recent incident in Office 365

Some customers' authentication tokens may have been invalidated as a side effect of the recent Office 365 downtime. API requests to these accounts would return 403 or 401 errors beginning on early Sept 29 morning, UTC. Please request users to check their historical service health at https://portal.office.com/adminportal/home?#/servicehealth for further information, including the scope, impact, and timeframe of downtime.