Forum Discussion
Anyone having issues with SharePoint Designer not authenticating?
Recently, we've started to experience a problem with SharePoint Designer where we cannot connect to a SharePoint Site. It attempts to login and prompts you for your Windows credentials repeatedly. ...
Can you try re-enable modern authentication by following this article and see if it helps.
https://blog.areflyen.no/2017/06/18/problem-with-connecting-to-sharepoint-online-in-office-365-with-powershell-sharepoint-designer-and-other-3-party-tools/