ASP.NET DISCO and WSDL pages were the web service APIs for customers who wanted to create a proxy for their web services. The retirement of ASP.NET web services was announced in 2013 and should not be used. We recommend using Microsoft Graph for remote operations where possible.
We will remove these pages from Microsoft SharePoint Online starting mid-August 2025 and ending in mid-September 2025.
Learn more: Removal of deprecated DISCO & WSDL aspx pages from SharePoint Online – Microsoft 365 Developer Blog