I just installed the 2025-10 cumulative update for Windows 11 on my laptop and am now getting errors on trying to run applications on localhost. Does anybody else have the same problem and is there a way to fix this?
I have one ASP.NET 4.6.2 application that I run as a site on my local IIS installation, via the hosts file, resolving the “app-name” there to 127.0.0.1. When I try to run it as http://, I get a “Site cannot be reached error” because of an “ERR_CONNECTION_RESET” error.
I also use Visual Studio in building .NET (.NET 8) web applications and trying to run (debug) these using IIS Express also now fails, with an “ERR_HTTP2_PROTOCOL_ERROR”.
And all this after I “2025-10 Cumulative Update for Windows 11 Version 24H2 for x64-based Systems (KB5066835) (26100.6899)” and “2025-10 Cumulative Update for .NET Framework 3.5 and 4.8.1 for Windows 11, version 24H2 for x64 (KB5066131)”. Is anybody else having similar issues and is a fix known?