Microsoft has fixed a bug in Windows 11, which disrupted localhost and HTTP/2

October Updates Windows 11 led to a serious problem with localhost, which is why applications using HTTP/2 connections to 127.0.0.1, started showing connection errors. Users encountered messages like ERR_CONNECTION_RESET и ERR_HTTP2_PROTOCOL_ERROR, especially when using tools like Visual Studio, SSMS Entra ID и Duo Desktop.

The problem appeared after installing updates KB5066835 (October) и KB5065789 (September)The crash affected both debugging processes and local authorization mechanisms, including Duo Prompt, which uses trusted endpoints and device security policy. Microsoft confirmed that The error is related to the HTTP.sys driver., which is used in the IIS server part and other local applications.

Microsoft has already released fix in the form of a Known Issue Rollback (KIR), which allows you to roll back problematic changes without uninstalling updates. To fix the error, users need to open the Windows Update Center Windows", click "Check for updates" and reboot the device - even if no updates are found, a reboot is required to activate the rollback.

It was previously reported that the temporary solution included Disabling HTTP/2 support via the registry Windows or installing the Microsoft Defender update, but neither method was guaranteed to work. The only stable solution before KIR was to completely uninstall the problematic updates via the command line.

Now Microsoft has officially confirmed the existence of the error and released secure automatic solution, which does not require manual intervention.