![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(268.8, 16%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EDU%3C/text%3E%3C/svg%3E)
I've tried all the suggestions provided. Unfortunately, the problem isn't resolved.
The Windows update removal method didn't work because I couldn't uninstall some updates.
The Windows team needs to provide an explanation for this!
Localhost not working anymore after 2025-10 cumulative update Windows 11
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(214.4, 80%, 30%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJV%3C/text%3E%3C/svg%3E)
Jan van Rhijn
270
Reputation points
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
Windows for business | Windows 365 Business
{count} votes
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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? -
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(281.6, 34%, 37%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EVO%3C/text%3E%3C/svg%3E)
Vic Omundsen 5 Reputation points2025-10-15T16:57:38.7666667+00:00 Uninstalling KB5066835 worked for me.
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Colby Butler 20 Reputation points2025-10-15T21:55:11.88+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.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(172.8, 39%, 26%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ERW%3C/text%3E%3C/svg%3E)
Rong Wang 0 Reputation points2025-10-16T04:07:51.85+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." -
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(112.00000000000001, 76%, 20%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESB%3C/text%3E%3C/svg%3E)
Semir BAx 0 Reputation points2025-10-16T04:23:46.5+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.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(201.6, 8%, 29%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EKA%3C/text%3E%3C/svg%3E)
Keith Alford 0 Reputation points2025-10-16T11:05:32.24+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.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(169.60000000000002, 69%, 26%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJB%3C/text%3E%3C/svg%3E)
Jason Baginski 106 Reputation points2025-10-16T13:11:53.6733333+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.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(153.6, 89%, 24%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMD%3C/text%3E%3C/svg%3E)
Marcelo Dênis 20 Reputation points2025-10-21T13:41:34.51+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.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(137.6, 79%, 23%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJ%3C/text%3E%3C/svg%3E)
Jaime 0 Reputation points2025-10-22T21:22:24.78+00:00 en serio microsoft no puedes estar 5 minutos sin avergonzarte a ti mismo ?
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Reza Rahmatzadeh 0 Reputation points2025-11-05T18:06:43.7833333+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?
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37 answers
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(230.39999999999998, 51%, 32%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAN%3C/text%3E%3C/svg%3E)
Alessandro Nespoli 10 Reputation points2025-10-16T06:46:27.9133333+00:00 A new installation of Windows 11 from the ISO, keeping files and applications, solved the problem in my case. I also couldn’t uninstall KB5066835, and modifying the registry keys had no effect. For the moment, I have disabled Windows automatic updates.
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Mohamed Mohsen 0 Reputation points2025-10-16T06:54:17.9766667+00:00 Open PS as Administrator then run the following script
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\HTTP\Parameters" -Name "EnableHttp2Tls" -Value 0 -Type DWord
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\HTTP\Parameters" -Name "EnableHttp2Cleartext" -Value 0 -Type DWord
Write-Host "Restarting IIS..."
iisreset
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EN Test 0 Reputation points2025-10-16T07:32:58.7166667+00:00 I also have this error, i can't even connect to "localhost" or "127.0.0.1" through HTTP. Every binding is there but doesn't work (HTTP or HTTPS). I've made an inplaceupgrade to 25H2 but nothing changed. Only uninstalling the Octoberupdates helped.
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Anders Mad 0 Reputation points2025-10-16T07:34:06.0966667+00:00 This worked for me - just the one:
wusa /uninstall /kb:5066835
Remember to pause Windows Update before.
I tried the regedits (disable HTTP2) and uninstalling kb5065789 (that I installed again) - but they did not work. I am using iisexpres on vs.net 2026.