Dimmed UAC-prompt in Windows freezes it when logged in Windows terminal with user other than the one logged in

[mabo003]

Windows Terminal version

1.21.3231.0

Windows build number

10.0.26100.0

Other Software

UAC-prompt that dims Windows causes this issue that freezes the entire OS.

Steps to reproduce

1. Start Windows Terminal either as Administrator (if the logged in user account does not have admin privileges) or as other user and use an account other than the one logged in.
2. Perform any action that triggers a UAC-promt in Windows. The setting needs to be set so it dims Windows.

Expected Behavior

UAC-prompt should appear as normal when Windows Terminal is started with a different account than the one logged in Windows.

Actual Behavior

Windows freezes when a UAC-prompt pops up for any reason, even when not concerning Windows Terminal. This happens when Windows Terminal is started with a different user than the one logged in Windows. This is recreated with a user that has admin privileges and unsure if this happens with accounts without admin privileges. When doing anything that triggers a UAC-prompt where it dims Windows it freezes it completely. The screen dims, but no UAC-prompt is displayed. You can CTRL+ALT+DEL back to Windows, but all windows and taskbar is almost non-responsive. You can control the cursor, but it seem to not register any clicks and nothing from the keyboard as well. The CPU works extra hard as it’s fan speeds up to max and there is a considerably delay when clicking on different windows like the are responding, but heavily delayed so Windows is not usable.

The only way to resolve the issue is to turn off the computer on the power button.

Cannot find any issue within the Event viewer. This issue has been reproduced on two different laptops with multiple reinstalls of Windows.

[jezuk]

Also experiencing this issue, found via: https://answers.microsoft.com/en-us/windowsclient/forum/all/issues-with-24h2-and-uac-prompts-and-screen-lock/5df375ae-4a6a-474f-baa8-107881a2e15f?page=1, also see page 2

The v1.21.2701.0 release mentions this issue is affecting 23H2 and and a fix is coming via Windows update.

I'm running 24H2 and have just installed the January Windows updates and the issue is still present.

[lecram89]

I'm also experiencing the same issue. My system is up-to-date.

[carlos-zamora]

Thanks for filing! Can you collect a full system performance trace of the issue /? You can use UIforETW. If you need help with using it, let us know. Happy to help 😊

[carlos-zamora]

Potentially related: #18105

[jezuk]

Hi @carlos-zamora, happy to collect a trace. Please let me know the instructions. Given the nature of the issue we may not be able to gracefully stop the trace when the system stops accepting input. Perhaps a scheduled reboot?

[dperez83]

Having the same problem. It's a nasty problem, Windows freezes completely when the UAC prompt would be shown. How can an application completely freezes Windows like that?

It's easy to reproduce on Windows 11 24H2 like @mabo003 explained.

[marcopixel]

@carlos-zamora

I can consistently reproduce the same issue by following the same steps highlighted by @mabo003.
Notably, this issue occurs on specific Windows 11 builds here - everything below 26100.2894 seems to work just fine.

I couldn't get a trace from this via UIforETW, is there maybe another option we could help fix this issue?
This problem is really annoying, especially in a development context as multiple elevated windows is nothing unusual...

Terminal build:

1.21.10351.0 (on all machines)

Affected Windows Builds:

❌ Issue can be reproduced: 26100.3037, 26100.3194
✔️ Not reproducable: 26100.2894