The October cumulative updates for Windows 11 produced a high-impact, widely reported regression that broke many localhost-based HTTP/2 connections on upgraded systems — leaving developers unable to debug IIS/IIS Express sites, blocking desktop apps that rely on local loopback services, and...
A wide-ranging October 2025 cumulative update for Windows 11 (KB5066835), and at least one related preview package, has broken many local IIS-hosted sites and developer workflows — causing ERR_CONNECTION_RESET, ERR_HTTP2_PROTOCOL_ERROR and outright failure of localhost-based services for...