SharePoint is not broken - it just does't work

App authentication woes on SharePoint (Token request failed. The remote server returned an error: (401) Unauthorized.)

This article explains how to get rid of sudden and unexplainable 401 Access Denied errors when trying to authenticate against a fairly fresh Microsoft 365 / SharePoint Online tenant. This issue seems to be caused by a long-ish project to finally retire ACS – Azure Access Control service) on SharePoint…Continue reading App authentication woes on SharePoint (Token request failed. The remote server returned an error: (401) Unauthorized.)