(Literally) Breaking: Changes to app authentication on SharePoint! 😵

This post was most recently updated on January 22nd, 2021. 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 (it’s retired everywhere else already!) Note: This is an updating story, as the situation with ACS is definitely… Developing. Yeah, let’s call it that. It’s … Continue reading (Literally) Breaking: Changes to app authentication on SharePoint! 😵