Just days after ending security updates for 500 million Windows 10 users, Microsoft is facing new trouble with Windows 11. According to Forbes, the company has confirmed that its latest update, KB5066835, has caused widespread problems – breaking local connections, disabling peripherals, and rendering Windows Recovery Environment nearly unusable. Microsoft has now issued an emergency patch to fix the chaos.
The problems began shortly after KB5066835 rolled out earlier this week. Reports from Windows Latest describe the update as a “total disaster,” warning that it breaks localhost connections – meaning apps and browsers can no longer connect to network services hosted on 127.0.0.1. This issue stems from a regression in the kernel-mode HTTP server (HTTP.sys), which mishandles HTTP/2 connections and resets them before they reach internal applications. As a result, developers running local web servers, APIs, or Internet Information Services (IIS) setups found their environments effectively unusable.
The update also introduced a separate bug in the Windows Recovery Environment (WinRE), blocking mouse and keyboard functionality entirely. Users attempting to troubleshoot, repair, or reset their systems discovered they couldn’t navigate menus at all. Microsoft has since acknowledged both issues, confirming that a fix is on the way but warning it could take up to 48 hours to appear on affected PCs. The company recommends checking for updates and rebooting systems manually even if no new patch is visible yet.
The problems don’t end there. Reports also point to compatibility issues with certain Logitech peripherals and random installation failures across different device configurations. The Register noted that while clean installs of Windows 11 version 24H2 appear unaffected, systems upgraded from previous builds are most at risk due to configuration conflicts triggered by the update.
Microsoft’s emergency patch aims to repair localhost functionality and restore input support in WinRE. However, users are being advised not to attempt manual registry or system file fixes found online, as these can cause instability or prevent Windows from booting.
For Windows 10 users, the timing is especially ironic. The company just ended free security updates for half a billion devices, offering only paid extended support through 2026. TechRadar warns that the final Windows 10 patch addressed dozens of security flaws, highlighting the risk for users who don’t opt in to Microsoft’s paid extension program.
The Register summed up the situation bluntly: within a single week, Microsoft’s final Windows 10 update expired, its Windows 11 patch broke local development tools, and its multimillion-dollar upgrade campaign exposed just how fragile its software ecosystem still is.