Saturday, October 18th 2025
Microsoft Breaks Localhost with Windows 11 October Update, Users Forced to Revert
Just two days after Windows 10 reached its end of life, issues with Microsoft's latest Windows 11 October update have begun to surface. Users on Microsoft Support Forums, Stack Overflow, and Server Fault have reported that the localhost functionality in Windows 11 is now broken. This problem is affecting millions of web developers who are unable to run their applications on their own PCs. The update, KB5066835, focuses on security and enhances the September-issued KB5065789 package with additional quality improvements. However, it disrupts the localhost function, a virtual hostname that allows a PC to serve as its own server. This feature is commonly used by local developers to test websites or fully developed web apps. The disruption has significantly impacted developers, including those using Windows 11 on their local servers or workstations for production purposes.
The community has managed to solve the issue by simply deleting the October KB5066835 package, alongside its September KB5065789 sibling, if the first package uninstall doesn't work. Software engineers have reported connection failures and HTTP/2 protocol issues impacting various development tools, including ASP.NET compilation processes and Visual Studio debugging functionality. Investigation has revealed that the problem originated in build version 26100.6899, with the root cause identified in HTTP.sys—a kernel-level Windows component responsible for managing HTTP traffic on local systems.
Update October 17, 15:30 UTC: Microsoft confirmed the issue and stated: "We are working on releasing a resolution for this issue in a future Windows update. We will provide an update when more information is available."This issue stack for Microsoft's latest Windows 11 keeps piling up. On Monday, Microsoft accidentally broke the Windows Media Creation Tool (MCT) just a day ahead of Windows 10's end-of-life. Last week, the company started mandating Online Accounts for Windows 11 installations, which are getting increasingly impossible to bypass. We need to see if this changes, and the constant influx of broken functionality drives users away from the Windows OS, or they are stuck with it for good.
Source:
via The Register
The community has managed to solve the issue by simply deleting the October KB5066835 package, alongside its September KB5065789 sibling, if the first package uninstall doesn't work. Software engineers have reported connection failures and HTTP/2 protocol issues impacting various development tools, including ASP.NET compilation processes and Visual Studio debugging functionality. Investigation has revealed that the problem originated in build version 26100.6899, with the root cause identified in HTTP.sys—a kernel-level Windows component responsible for managing HTTP traffic on local systems.
Update October 17, 15:30 UTC: Microsoft confirmed the issue and stated: "We are working on releasing a resolution for this issue in a future Windows update. We will provide an update when more information is available."This issue stack for Microsoft's latest Windows 11 keeps piling up. On Monday, Microsoft accidentally broke the Windows Media Creation Tool (MCT) just a day ahead of Windows 10's end-of-life. Last week, the company started mandating Online Accounts for Windows 11 installations, which are getting increasingly impossible to bypass. We need to see if this changes, and the constant influx of broken functionality drives users away from the Windows OS, or they are stuck with it for good.
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105 Comments on Microsoft Breaks Localhost with Windows 11 October Update, Users Forced to Revert
Keep updating that OS guys, go go.
does 127.0.0.1 fail completely or just the "localhost" alias?
If the latter, a hosts file edit could serve as a temp workaround. Still a pretty wtf thing to do.
EDIT: Reading more, sounds like a HTTP protocol issue more. Confusing to say the least.
If the latter, a hosts file edit could serve as a temp workaround. Still a pretty wtf thing to do.
EDIT: Reading more, sounds like a HTTP protocol issue more. Confusing to say the least.
The future of Windows is dire.
Not running a server, but my main PC is on 26200.6899 and if I ping both localhost and 127.0.0.1 and get near instant responses. Not sure how to test this issue otherwise.
I said it repeatedly - the only way to save Windows from degradation is through regulation. Break MS up and force Windows to be a separate entity developed by a non-profit. From the very beginning, the concept of the dominant main desktop OS being in the hands of a profit driven globo corpo was a complete nonstarter. The very paradigm of constant growth inevitably leads to rot setting in and making the development of good products essentially impossible.
OnasiBreak MS up and force Windows to be a separate entity developed by a non-profit. From the very beginning, the concept of the dominant main desktop OS being in the hands of a profit driven globo corpo was a complete nonstarter.You don't know history at all. MS-DOS was developed by Microsoft for the IBM PC. From the very beginning, the dominant desktop OS has ALWAYS been in the hands of a profit driven corporation, whether it's Mac OS or MS-DOS and its successors. And that's why Windows is the dominant OS, while FOSS alternatives are not.
Let me know when a FOSS OS drives the development of graphics technology. Or has a unified integration of office software, device management, cloud services, user management, etc.
Works on my Windows 10 machine.
This issue stack for Microsoft's latest Windows 11 keeps piling up.This is what happens when the supposedly best innovation (AI) writes code.
With a friendly smile,
Fred.
I can't for the life of me fathom who or what they have outsourced testing of Windows updates to?
They are breaking more and more, more critical and so obviously easy to spot features that it feels like they truly are using chatgpt to run and analyze their build tests.
They are breaking more and more, more critical and so obviously easy to spot features that it feels like they truly are using chatgpt to run and analyze their build tests.
halcyonI can't for the life of me fathom who or what they have outsourced testing of Windows updates to?Windows Insiders.
Which isn't a good idea if you ignore their feedback for months anyway
LastDudeALiveYou don't know history at all. MS-DOS was developed by Microsoft for the IBM PC. From the very beginning, the dominant desktop OS has ALWAYS been in the hands of a profit driven corporation, whether it's Mac OS or MS-DOS and its successors. And that's why Windows is the dominant OS, while FOSS alternatives are not.I know history just fine. The world has changed and at this point what MS was during DOS days has little to no relevance to what MS is now. Note how I did not suggest Windows to go FOSS. I just have absolutely no trust in MS to handle Windows anymore as it is, full stop.
Let me know when a FOSS OS drives the development of graphics technology. Or has a unified integration of office software, device management, cloud services, user management, etc.
MS users on the early update cycle are still the QA team... Is this just Windows 11 or Server builds on this code as well...
No idea why anyone who has the option / able to use LTSC wouldn't go that way, or at least demand payment for testing MS code for them all the time ?
No idea why anyone who has the option / able to use LTSC wouldn't go that way, or at least demand payment for testing MS code for them all the time ?
Leave them raccoons alone!! They're trying their best, OK?!
not really surprised there is always something breaking windows 11 hence why i'm still on 10.
I just tested on my PC with jupyter notebooks and checked to make sure the bad patch is installed. Everything appears to work fine for me so I'm guessing the issue is subtle and very configuration dependent.
Was Copilot talking to himself a bit too much, so they tried to somehow stop him?
Windows has been on an uncontrolled downward spiral after Windows 7, but you mean to tell me this is the OS that replaces Windows 10?
Microsoft with their issues:
mb194dcIs this just Windows 11 or Server builds on this code as well...Server runs on LTSC code so most likely it's affected as well.
If nothing else, I'm getting a hell of a laugh outta this. Imagine having issues like this the moment you drop support for Win10—fate could not write a funnier joke if it tried!
The end of Win 10 and the mass migration to Win 11, increased computer sales, AI code bringing in more money for Microsoft, so everything is fine.
Some end users had problems, but who cares, money is pouring in like rain.
Some end users had problems, but who cares, money is pouring in like rain.
LastDudeALiveLet me know when a FOSS OS drives the development of graphics technology.Vulkan says hi.
ymdhisWorks on my Windows 10 machine.Well, no, this patch doesn't. But that's probably a good thing.
All sorts of apps use localhost, this is a weird bug if functionality of it got broken, its like there wasnt even basic testing by the dev that made the patch, wtf.
As an example Firefox uses it to connect to itself.
As an example Firefox uses it to connect to itself.
R-T-BVulkan says hi.Can you name me a feature that Vulkan has innovated and DirectX has copied, instead of the other way around? That's why I specified "drives the development," because Vulkan just ends up copying whatever Microsoft innovates with DirectX.
