IIS Express not working after updating to Visual Studio 2022 to 17.14.17

[JKDevz]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Launching the app on IIS Express (Start with Debugging) does not launch the app at all.

This only started after I updated Visual Studio 2022 to version 17.14.17, yesterday.

I found an existing issue (#63160) but it has been closed for some reason, despite myself and other comments noting they are still encountering this behaviour.

Expected Behavior

A browser window appears, and the application runs and can be interacted with as expected.

Steps To Reproduce

1. Open any web application with Visual Studio 2022, running version 17.14.17
2. Set launch profile to IIS Express (Start with Debugging, on IIS Express)
3. Run the application
4. Browser window appears, IIS appears in system tray, but application does not start

Exceptions (if any)

• Breakpoints don't even trigger, so the app in its entirety seems to not start.
• A browser window does appear and IIS does appear in the system tray, but the app hasn't launched.
• Launching with HTTP and HTTPS (Kestrel) works fine, but for my use case I require IIS Express.

Checking the ports, I can see that the port in my launchsettings.json is being used only when I run the app, but they are being occupied by the System process (indicated by PID 4).

Command Prompt Output:

C:\Windows\System32>netstat -ano | findstr 56553
  TCP    0.0.0.0:56553          0.0.0.0:0              LISTENING       4
  TCP    [::]:56553             [::]:0                 LISTENING       4

I've tried clearing and resetting my certs, checking my certs in certsmgr, deleting applicationhost.config in .vs.
This doesn't seem to be an issue with SSL or system certficates. I've tried switching ports but the system always occupies the port I end up using.

The only thing I can think of is rolling back the update.

Any assistance would be greatly appreciated.

.NET Version

9.0.306

Anything else?

IDE: VS 2022
IDE Version: 17.14.17

OS: Windows 11
OS Version: 10.0.26100 Build 26100

[JKDevz]

Issue is unrelated to Visual Studio, instead it is due to Windows Updates issued on October 15th 2025.

You can view the issue and solution (as of posting) below to resolve this, which involves deleting 3 Windows Updates from your device and (possibly) rolling back your Visual Studio version from 17.14.17 > 17.14.16.

Server Fault Issue:
https://serverfault.com/questions/1193405/http-2-protocol-error-connecting-to-localhost-web-sites