Microsoft's October Windows 11 update has managed the impressive feat of breaking localhost, leaving developers unable to access web applications running on their own machines. The problem first surfaced on Microsoft's own support forums and quickly spread to Stack Overflow and Server Fault after the October 2025 cumulative update (KB5066835) landed, which appears to have severed Windows' ability to talk to itself. Developers describe HTTP/2 protocol errors and failed connections affecting every...