https://www.theregister.com/2025/10/16/windows_11_update_localhost/ # # Sign in / up The Register # # # Topics Security Security All SecurityCyber-crimePatchesResearchCSO (X) Off-Prem Off-Prem All Off-PremEdge + IoTChannelPaaS + IaaSSaaS (X) On-Prem On-Prem All On-PremSystemsStorageNetworksHPCPersonal TechCxOPublic Sector (X) Software Software All SoftwareAI + MLApplicationsDatabasesDevOpsOSesVirtualization (X) Offbeat Offbeat All OffbeatDebatesColumnistsScienceGeek's GuideBOFHLegalBootnotesSite NewsAbout Us (X) Special Features Special Features All Special Features Cybersecurity Month Cloud Infrastructure Month Datacenter Networking Nexus The State of Storage European Supercomputing AI Infrastructure Month Spotlight on RSAC AI Software Development Week Disaster Recovery Week Nvidia GTC Ransomware in Focus The Future of the Datacenter VMware Explore Vendor Voice Vendor Voice Vendor Voice All Vendor Voice Money Movement Hub The BigQuery Difference AWS Global Partner Security Initiative Amazon Web Services (AWS) New Horizon in Cloud Computing (X) Resources Resources Whitepapers Webinars & Events Newsletters [oses] OSes 37 comment bubble on white Windows 11 update breaks localhost, prompting mass uninstall workaround 37 comment bubble on white Microsoft's quality control department caught napping again icon Owen Hughes Thu 16 Oct 2025 // 13:11 UTC # Microsoft's October Windows 11 update has managed the impressive feat of breaking localhost, leaving developers unable to access web applications running on their own machines. The problem first surfaced on Microsoft's own support forums and quickly spread to Stack Overflow and Server Fault after the October 2025 cumulative update (KB5066835) landed, which appears to have severed Windows' ability to talk to itself. Developers describe HTTP/2 protocol errors and failed connections affecting everything from ASP.NET builds to Visual Studio debugging sessions. Security nightmare stories needed! Boss get the company hacked because he taped passwords to his monitor? Coworker get phished by a Nigerian prince? Share the dirty details and they might appear in a future edition of PWNED, our new weekly feature about the worst security breaches that never should have happened. Drop us a line at pwned@sitpub.com. Your anonymity is guaranteed. The bug, introduced in build 26100.6899, has been traced to HTTP.sys, the Windows kernel component that handles local HTTP traffic. Developers have found that uninstalling KB5066835, and in some cases its sibling KB5065789, restores localhost functionality. Others have discovered a temporary workaround that involves manually disabling HTTP/2 in the registry, which works but feels a bit like using a sledgehammer to swat a fly. [oses] At the time of writing, Microsoft had yet to acknowledge the issue. Users report mixed results when trying to reinstall the patch or roll forward to newer builds. The problem appears to vanish on clean installs of Windows 11 24H2, suggesting that the error stems from a conflict in how the update interacts with existing system configurations, rather than being a universal bug. [oses] [oses] In the meantime, moderators on Stack Overflow have already locked multiple posts and Server Fault threads are filled with frustrated devs trying to get their local servers running again. * Schleswig-Holstein waves auf Wiedersehen to Microsoft stack * What do we want? Windows 10 support! When do we want it? Until 2030! * Who gets a Mac at work? Here's how companies decide * No account? No Windows 11, Microsoft says as another loophole snaps shut All this comes as Microsoft pushed its final update for Windows 10 this week, officially ending support for the decade-old OS and urging users to move to Windows 11. The transition hasn't exactly been buttery smooth. Microsoft's Windows 11 media creation tool also stopped working the day before, potentially affecting users trying to upgrade, and the same patch cycle saw end-of-support deadlines for Office 2019 and multiple server products. All this means that, within the same week, Microsoft's installer broke, its new OS borked local development, and Redmond's multimillion-dollar upgrade push instead highlighted how fragile its ecosystem still is. [oses] It's almost enough to make you nostalgic for Clippy. We said almost. 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No Windows 11, Microsoft says as another loophole snaps shut Workaround sent to the big OOBE in the sky with latest Insider builds SaaS7 Oct 2025 | 151 Hundreds of millions of business PCs are still on Windows 10 as D-Day nears canalys emea forum 2025 It's the end of support as we know it and users feel fine SaaS9 Oct 2025 | 69 Rethinking application delivery for the hybrid world Why bake apps into your OS when you can deliver them as a side dish? Sponsored feature [oses] Windows 10 refuses to go gentle into that good night Rage, rage against the dying of the free security updates OSes2 Oct 2025 | 73 Brits sitting on PS1.6B gold mine of Windows 10 junk as support ends Recyclers reckon millions of obsolete PCs could yield a small fortune in precious metals Personal Tech8 Oct 2025 | 90 Healthcare lags in Windows 11 upgrades - and lives may depend on it Interview Most orgs still on Windows 10, so maybe don't get ill after October 14 OSes30 Sep 2025 | 13 What do we want? Windows 10 support! When do we want it? Until 2030! Updated Protesters slam forced obsolescence outside Microsoft's office OSes14 Oct 2025 | 66 Feeling lonely? Microsoft Copilot can now listen to your every word, watch your screen We've seen this before and it was called Cortana or Clippy AI + ML16 Oct 2025 | 16 Hundreds of orgs urge Microsoft: don't kill off free Windows 10 updates Petitions pile up on Satya's desk while Windows 7 mysteriously surges back from the grave OSes1 Oct 2025 | 86 Microsoft digs up Vista-era animated wallpaper for Windows 11. Here's how to get it hands on Debuted in 2007, an old feature is coming back OSes26 Sep 2025 | 43 Windows 11 gets a fresh Start in latest Canary build Meanwhile, Microsoft resurrects Edit and kills .NET 3.5 SP1 on demand OSes9 Oct 2025 | 25 The Register icon Biting the hand that feeds IT About Us* * Contact us * Advertise with us * Who we are Our Websites* * The Next Platform * DevClass * Blocks and Files Your Privacy* * Cookies Policy * Privacy Policy * Ts & Cs * Do not sell my personal information Situation Publishing Copyright. All rights reserved (c) 1998-2025 no-js