Feature update to Windows 10, version 20H2: 2020-09 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10 Version 2004 for x64 (KB4576478)
ClickOnce will no longer download applications from untrusted servers which use NTLM authentication, but, instead, will fail with “Authentication failed”. Sites in the Local Intranet and Trusted sites zones will continue to authenticate as before.
ClickOnce is a deployment technology that enables you to create self-updating Windows-based applications that can be installed and run with minimal user interaction. Visual Studio provides full support for publishing and updating applications deployed with ClickOnce technology if you have developed your projects with Visual Basic and Visual C#. For information about deploying Visual C++ applications, see ClickOnce Deployment for Visual C++ Applications.