Microsoft fixes Windows bug breaking localhost HTTP connections

Microsoft addressed a regression in HTTP.sys introduced by recent Windows updates (notably KB5066835 and a KB5065789 preview) that caused HTTP/2 localhost (127.0.0.1) connections and IIS-hosted sites to fail on Windows 11 and Windows Server 2025, producing errors like ERR_CONNECTION_RESET and ERR_HTTP2_PROTOCOL_ERROR; the company provided mitigation steps (check for updates and reboot), deployed Known Issue Rollback for many users, and published KIR group policy guidance for enterprise-managed devices while a permanent fix is planned in a future update.