Localhost not working anymore after 2025-10 cumulative update Windows 11

Jan van Rhijn 270

Hi,

Since the last cumulative update of 2025-10 I can not access applications via localhost anymore. It looks like I am not the only one with this issue: https://serverfault.com/questions/1193405/http-2-protocol-error-after-windows-update and https://stackoverflow.com/questions/79790827/localhost-applications-failing-after-installing-2025-10-cumulative-update-for-w

When the update (KB5066835) is removed, everyhting works again.

This is affecting local development as well as business applications

Cheers,

Jan

Jan van Rhijn 270 Reputation points

2025-10-15T14:09:07.8366667+00:00

On a fresh install of Windows (and updated to the latest version), I don't have this issue anymore. I am checking what the differences are between my current Windows and the freshly installed one.
Can more people verify that this issue is resolved on a fresh install of Windows?
Vic Omundsen 5 Reputation points

2025-10-15T16:57:38.7666667+00:00

Uninstalling KB5066835 worked for me.
Colby Butler 20 Reputation points

2025-10-15T21:55:11.88+00:00

I apologize if this has already been answered, but since I've rolled back to a version before [KB5066835], is it likely that a patch will be available when I check for Windows updates? I've paused updates for now, so I want to ensure I don't miss a potential fix.
Rong Wang 0 Reputation points

2025-10-16T04:07:51.85+00:00

Uninstalling KB5066835 worked for me. +1
but my colleague's attempt to uninstall KB5066835 was also unsuccessful, but they succeeded after subsequently removing KB5065789."
Semir BAx 0 Reputation points

2025-10-16T04:23:46.5+00:00

If you can’t uninstall the KB updates, try this first: open Windows Features and turn off Hyper-V, IIS, Windows Process Activation Service, and both .NET Framework 3.5 and 4.8.
Keith Alford 0 Reputation points

2025-10-16T11:05:32.24+00:00

I had the same problem. Uninstalling KB5066835 by command line worked for me and fixed localhost. The annoying thing is that it keeps reinstalling itself so now I have to avoid restarting my system.
Jason Baginski 106 Reputation points

2025-10-16T13:11:53.6733333+00:00

Thank you for this thread. Ran into the same issue trying to debug a website with Visual Studio this morning and adding the two registry keys got it working. MS needs to make a statement of intent to fix, especially since this was the "last" update for W10.
Marcelo Dênis 20 Reputation points

2025-10-21T13:41:34.51+00:00

In my case, my Windows 11, which is 22H2, probably received the mandatory update that breaks localhost after installation. All the solutions I found were for 24H2 and 25H2, but not for 22H2, yet the problem is the same: localhost stopped working.
Jaime 0 Reputation points

2025-10-22T21:22:24.78+00:00

en serio microsoft no puedes estar 5 minutos sin avergonzarte a ti mismo ?
Reza Rahmatzadeh 0 Reputation points

2025-11-05T18:06:43.7833333+00:00

I’d prefer to receive a hotfix update from Microsoft rather than manually uninstalling the latest update. Will a hotfix be released for it?

37 answers

MICKEY LYSHOLM NIELSEN 10 Reputation points

2025-10-15T13:15:28.2833333+00:00

Added the keys here as well but it dosn't solve the problem.
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2 people found this answer helpful.
Jason Chu 20 Reputation points

2025-10-15T13:26:53.8166667+00:00

The keys also didn't fix it for me.
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AD 10 Reputation points

2025-10-15T13:27:36.7366667+00:00

uninstalling KB5066835 did not fix, but uninstalling KB5066835 and KB5065789 did fix.
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2 people found this answer helpful.
Steven Hsiao 0 Reputation points

2025-10-15T14:17:24.73+00:00

This work for me
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Harry Hamilton 10 Reputation points

2025-10-15T13:31:29.1366667+00:00

Tried multiple possibilities...

Even tried the suggestion in StackOverFlow

Rebooted after each attempt and still doesn't work.
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2 people found this answer helpful.
Knut Hunstad 15 Reputation points

2025-10-15T13:40:22.7366667+00:00

Same here. And I also tried starting Chrome with --disable-http2, but that didn't help either. Our application goes to a localhost-URL at the end of the sign-in process, which shows "Page not found" now.

YDPages 0 Reputation points

2025-10-15T23:23:49.9266667+00:00

uninstalled Both Patches

wusa /uninstall /kb:5066835

wusa /uninstall /kb:5067360

Removed and reinstalled IIS and all Features.
Reviewed Configurations and the issue is still blocking. unable to browse static content.
http://localhost:82/iisstart.htm

Would a Cert Help?

unknown 0 Reputation points

2025-10-16T05:28:41.2533333+00:00

but yes uninstalling this update fixed the issue with the localhost i was having issues with my streamdeck not allowing me to link my twitch account to a certain plugin it would give me error connection reset and stuff but after removing KB5066835 fixed my problem but hope they put out a patch so we can still use this update tho
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Guilherme Grudtner 10 Reputation points

2025-10-15T14:48:41.0366667+00:00

The problem appears to me today. So I Added the keys and uninstall the 5066835 and 5066131.

the error ERR_HTTP2_PROTOCOL_ERROR disappears but now I have the error ERR_CONNECTION_RESET
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SkitteryJim 0 Reputation points

2025-10-16T00:52:27.1566667+00:00

Any updates on resolving the ERR_CONNECTION_RESET issue?

SkitteryJim 0 Reputation points

2025-10-16T03:48:43.4666667+00:00

Now having issues getting into Azure:

Unable to sign in: An HttpListenerException occurred while listening on http://localhost:60450/ for the system browser to complete the login. Possible cause and mitigation: the app is unable to listen on the specified URL; run 'netsh http add iplisten 127.0.0.1' from the Admin command prompt. ERR_CONNECTION_RESET and the netsh command didn't help.
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Ryan Heldt 20 Reputation points

2025-10-15T18:18:11.9033333+00:00

Hi Everyone-

After trying all the recommendations here without much luck, I downloaded a fresh Win 11 ISO from https://www.microsoft.com/en-us/software-download/windows11 and reinstalled Windows on top of itself, telling the installer to keep my software and settings. It took about an hour, but so far that seems to have fixed the IIS problems on my machine.

Now I wish I could get my morning back.
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Kresimir Grozdek 0 Reputation points

2025-10-15T20:16:57.1833333+00:00

I had the same situation. After I uninstalled all the updates from 15.10., nothing changed and IIS still didn't work. After that, I reinstalled Windows just like you did, and now IIS works. It's a shame on Microsoft for releasing such updates without testing them beforehand. This is already the third time this year that I had to reinstall Windows because of an unreliable update. Linux here I come! From now on, I will only use Windows for old applications, and only on a virtual machine. Enough is enough.
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