A new Windows 11 update, KB5066835, is causing significant issues by breaking localhost connections, preventing locally hosted apps from communicating with the network. Users are experiencing installation failures and problems with peripherals and accessories. Microsoft has acknowledged the issue and is rolling out an emergency patch, which may take over 48 hours to reach affected PCs. The update disrupts the kernel-mode HTTP server (HTTP.sys), leading to connection failures for apps trying to access localhost. Additionally, the update renders the Windows Recovery Environment (WinRE) unusable, as mice and keyboards do not function within it. Users attempting to reinstall the patch or upgrade to newer builds have reported inconsistent results, with fresh installs of Windows 11 24H2 not experiencing the same issues. Caution is advised against attempting unofficial fixes, as they may destabilize the system. Windows 10 users should ensure their systems are updated with the final security patches or consider purchasing Extended Security Updates for continued support.