Enabling Custom App Authentication
If you are using a custom authentication method with your application you must manually enable it using PowerShell cmdlets.
Run the following PowerShell cmdlets on Windows PowerShell:
-
Install the SharePoint Online PowerShell module (if you don't have it) and execute the following command:
$orgName = "<your-org-name>"
-
Authenticate as the SharePoint administrator using the following command:
Connect-SPOService - Url https://$orgName-admin.sharepoint.com
-
Enable the custom application authentication using the following command:
Set-SPOTenant -DisableCustomAppAuthentication $false