Microsoft's quality control department caught napping again:
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.
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.
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.
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.
It's almost enough to make you nostalgic for Clippy. We said almost.
Hopefully this is all fixed before this story gets posted.
(Score: 3, Interesting) by tekk on Sunday October 19 2025, @07:23PM (6 children)
Is the article wrong or does Windows for some reason actually need explicit kernel http support? That sounds insane. I've known of in-kernel http *servers* for performance reasons, but never protocol support needed for userland applications.
(Score: 2) by RamiK on Sunday October 19 2025, @07:49PM (3 children)
Might be a weird hosts file thing (\Windows\System32\drivers\etc\hosts) like how debian's /etc/hosts has a few extra entries for localhost like 127.0.1.1, only the other way around.
compiling...
(Score: 3, Insightful) by mcgrew on Sunday October 19 2025, @08:47PM
Might be a weird hosts file thing
It's a shitty operating system thing. Get a computer with a REAL operating system!
Donald Trump is a mixture of Warren Harding, Calvin Coolidge, and Herbert Hoover, multiplied by ten.
(Score: 2) by tekk on Monday October 20 2025, @08:31AM (1 child)
That shouldn't be http-specific though. I looked it up thinking that maybe http/2 required encryption, so maybe there was some weird support to MITM yourself, but HTTP/2 does not mandate encryption as far as I know.
(Score: 2) by RamiK on Monday October 20 2025, @12:51PM
DNS over HTTPS (DoH) is done via the http/2 stack and it bypasses the hosts file so I don't see any reason why it can't fuck up localhost handling specifically.
compiling...
(Score: 2) by driverless on Monday October 20 2025, @04:15AM
Came here to say the same thing. WTF does your kernel need HTTP, a.k.a. the web vulnerability engine, support?
(Score: 3, Funny) by darkfeline on Friday October 24 2025, @08:13AM
How else would the kernel serve you ads?
Join the SDF Public Access UNIX System today!
(Score: 0) by Anonymous Coward on Sunday October 19 2025, @11:11PM (3 children)
Stick to Win 10 or 7 if you want to use Windows. Maybe in 2032 Win 11 will be OK for serious use.
(Score: 3, Interesting) by Anonymous Coward on Monday October 20 2025, @12:06AM (1 child)
Win 11 is too much like my 30 year old van.
I took it to a shop yesterday cuz my knees were bothering me.
It has so many patches , workarounds , duct tape , and baling wire holding it together. Old parts wearing out
Few people can even change the oil in it correctly.
Things I learned from my experience:
- Some professionals do not use the dipstick.
- Some professional shops do not carry spare oilpan drain gaskets and will insist on ordering a whole new drain plug, which of course, nobody has.
I should have called in a local mobile mechanic.
In the case of Microsoft:
It's held together by numerous updates and patches. A substandard design hastily released to meet an arbitrary deadline. I get the idea no-one knows how it all works.
Things I learned from others experience:
- They use their customers to test updates.
- If Microsoft screws it up, it's up to you to get it going again.
I should be using more robust OS.
A Microsoft System is Not the Family Bible! That Bible will pass through generations. It's a good place to record family births, deaths, and weddings. Heck, I still use my old VisiCalc to do taxes. It's almost 40 years old now. It originally ran on a PC clone. It now runs on a P166. I still use a floppy disk. The VC.com executable and about 35 years of tax returns are on that floppy, which is backed up in triplicate on other media.
Every year, I crack open last year's taxes, edit the changes, copy the new numbers to the new forms with pen, and mail it in . I avoid any activity that stirs up reporting things...as the cost of preparing government required tax paperwork had been exceeding any monies earned.
I'd simply rather live a frugal lifestyle than attract teams of government functionaries all looking for people ignorant of tax loopholes.
( This, like a lot of my rants, went terribly off topic. So I will post AC. )
(Score: 0) by Anonymous Coward on Monday October 20 2025, @03:16AM
Seems on-topic to me. You've described a perfect use-case for not "upgrading" a perfectly good working computer, doing, of all the crazy things, computing.
(Score: 4, Funny) by Reziac on Monday October 20 2025, @02:47AM
It's a cure for Window schizophrenia.
At least, it no longer exhibits the symptom of talking to itself.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 3, Informative) by Azuma Hazuki on Monday October 20 2025, @05:37AM (2 children)
...was prescient. I have an old friend to thank for convincing me to make the switch back then (and curse for convincing me to start it on Gentoo of all things!).
I am "that girl" your mother warned you about...
(Score: 1) by DECbot on Monday October 20 2025, @03:15PM (1 child)
Your friend did you a favor making you try Gentoo first. Now any other distro, besides Linux From Scratch, will look so easy and user friendly. You'll never get that urge to test out Gentoo again. Been there, done that, the compiler is still compiling, you've got the t-shirt and achievement medal--and a bit of knowledge too. Gentoo has got to be the monkey's paw curse for the wish "I want the best, fastest operating system available for my hardware."
cats~$ sudo chown -R us /home/base
(Score: 2) by Azuma Hazuki on Tuesday October 21 2025, @12:51AM
Two decades and change later I am *still* running it. It hurts sometimes, but no other distro really feels right, you know? Void is really nice on older hardware though.
I am "that girl" your mother warned you about...