Widespread IIS Failures Follow Recent Windows 11 Updates
Microsoft has confirmed that recent Windows 11 updates are causing significant disruptions to IIS (Internet Information Services) websites, creating headaches for system administrators and web developers. The problematic updates—KB5066835 for Windows 11 24H2, 25H2, and Windows Server 2025, along with its preview version KB5065789—have been breaking localhost connections and various authentication mechanisms, resulting in widespread “ERR_CONNECTION_RESET” errors across affected systems. This situation echoes previous Windows 11 update complications that have challenged enterprise environments.
The core issue stems from conflicts between the Windows updates and the HTTP stack (http.sys) driver, which serves as the foundation for many web services on Windows platforms. Microsoft’s documentation indicates that “server-side applications that rely on HTTP.sys may experience issues with incoming connections” following installation of updates released on or after September 29, 2025. The problem manifests particularly severely for websites hosted on localhost and other IIS connections, effectively halting development and testing workflows.
Understanding the Technical Breakdown
The HTTP.sys driver, a kernel-mode component responsible for HTTP request processing in Windows, appears to be rejecting connections that would normally be accepted. This disruption affects not only web page loading but also various authentication protocols that depend on localhost communications. System administrators report that the issue doesn’t affect all environments uniformly, with Microsoft noting that “device’s internet connectivity, as well as timing of recent update installation and device restarts” may influence whether the problem manifests.
The selective nature of the disruption has complicated troubleshooting efforts, as some systems continue functioning normally while others experience complete IIS failure. This variability suggests the issue may involve specific configuration states or timing conditions during update installation.
Microsoft’s Interim Solution
While working on a permanent fix, Microsoft has directed IT administrators to implement a Known Issue Rollback via Group Policy as an immediate workaround. The specific policy can be located in Computer Configuration > Administrative Templates section, with the downloadable package titled “Windows 11 24H2, Windows 11 25H2 and Windows Server 2025 KB5066835 251015_22001 Known Issue Rollback.msi.”
This approach represents Microsoft’s standard protocol for addressing update-related complications, though system administrators must weigh the security implications of rolling back patches that may contain important vulnerability fixes. The temporary nature of this solution underscores the complexity of resolving conflicts within core Windows components.
Broader Industry Context
Such technological disruptions occur alongside significant financial developments in the tech sector, including Harvard’s remarkable endowment growth despite broader economic challenges. Meanwhile, investment firms continue backing technology initiatives, as evidenced by Asymmetric Capital Partners securing $137 million for strategic investments in computing infrastructure and industrial technology.
Even as terrestrial technology faces challenges, astronomical research continues advancing, with recent discoveries including a mysterious glow in the Milky Way that may represent groundbreaking astrophysical phenomena, demonstrating how computational challenges on Earth coincide with cosmic discoveries.
Immediate Actions for Affected Systems
Organizations experiencing IIS failures should:
- Immediately assess whether recent Windows updates correlate with web service disruptions
- Implement the Known Issue Rollback via the specified Group Policy if confirmed affected
- Monitor Microsoft’s Windows Health dashboard for updates on a permanent resolution
- Consider testing environments that can validate future updates before production deployment
Microsoft has not provided a timeline for a comprehensive fix but continues investigating the root cause of the HTTP.sys compatibility issue. System administrators are advised to maintain current backups and develop contingency plans for web services that might be affected by similar update-related disruptions in the future.
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