Disaster, Windows 11 October update prevents sites from running locally
Just after having fixed a driver issue that prevented 24H2 updating for many PCsMicrosoft has just confirmed a major malfunction affecting recent versions of Windows 11 (Windows 11 version 24H2, Windows 11 version 25H2, Windows Server version 2025).
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Since the installation of the October 2025 updates (KB5066835 and KB5065789, released during Patch Tuesday), many websites hosted directly on Windows computers refuse to display. Users see a cryptic error message: ERR_CONNECTION_RESET, indicating that the connection has been abruptly terminated.
A conflict between security and normal operation
The problem mainly concerns developers, web agencies and companies who test their sites locally, that is to say directly on their machine before putting them online. These working environments, essential for designing and verifying web applications, became unusable overnight. Even the address http://localhost, used by thousands of professionals daily, no longer responds.
The origin of the malfunction lies in a conflict between recently deployed security patches and IIS, the web server integrated into Windows. More precisely, it is the HTTP.sys driver, responsible for managing internet connections at the system level, which contradicts the changes made by updates KB5066835 and KB5065789. Microsoft recognizes that the problem does not manifest itself in the same way everywhere: certain computers remain spared depending on their network configuration and the history of restarts carried out.
A patch offered to admins
For now, the publisher offers IT administrators a temporary workaround: download and deploy an MSI file called “Known Issue Rollback” via Windows Group Policies. This interim fix is configured in the “Computer Configuration > Administrative Templates” section and overrides changes made to the HTTP.sys driver without completely uninstalling security updates.
In the meantime, Microsoft is working on a definitive fix, the release date of which has not been communicated.
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