Microsoft has acknowledged that recent updates to Windows 11 (specifically the 24H2 and 25H2 versions) are causing issues with IIS (Internet Information Services) websites, which became apparent following October’s Patch Tuesday release. This problem arises from a conflict in the Windows HTTP stack driver (HTTP.sys), resulting in “ERR_CONNECTION_RESET” errors. Users may encounter these issues when trying to access localhost loopbacks or when connecting to other IIS-based websites.
The affected updates, which were rolled out on or after September 29, include KB5066835 and KB5065789. Microsoft has indicated that server-side applications that depend on HTTP.sys may have difficulties with incoming connections, leading to failures of IIS websites or entire blank pages. This bug specifically impacts localhost setups and systems used for development.
While not all devices may experience this issue—variances in internet connectivity, system timing, or the order in which updates were installed could influence this—those affected face disruptions particularly in internal testing environments and hosted web applications.
To mitigate the issue temporarily, IT administrators have been directed to apply a known issue rollback (KIR) through a specific Group Policy configuration. This will help restore stability to the system without the need to uninstall the update entirely. Microsoft has provided a dedicated download link for administrators looking to implement this rollback for 24H2, 25H2, and Windows Server 2025.
On a more positive note, Microsoft has recently lifted an upgrade block for Windows 11 24H2 after addressing a third-party driver conflict that had obstructed installations.