Regression: Environment Variables tool crashes immediately in elevated mode (PowerToys 0.100.1–0.100.2, Windows 11 25H2)

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### Microsoft PowerToys version

0.100.2

### Installation method

PowerToys auto-update

### Area(s) with issue?

Environment Variables

### Steps to reproduce

Install PowerToys 0.100.1 or 0.100.2
Open Environment Variables
Attempt to edit system environment variables (requires elevation)
via UI

or by launching directly:

Start-Process "$env:LOCALAPPDATA\PowerToys\WinUI3Apps\PowerToys.EnvironmentVariables.exe" -Verb RunAs
Application closes immediately without UI

### ✔️ Expected Behavior

Environment Variables tool should:

Launch elevated UI successfully
Allow editing system environment variables

### ❌ Actual Behavior

Window appears briefly then exits immediately
No usable UI in elevated mode
No crash dialog shown (silent termination)
Non-elevated mode works but only supports user variables

Event Viewer logs

Application Error (Event ID 1000):

Faulting application name:
PowerToys.EnvironmentVariables.exe

Faulting module name:
Microsoft.UI.Windowing.dll

Exception code:
e0464645

Windows Error Reporting:

APPCRASH
PowerToys.EnvironmentVariables.exe
Microsoft.UI.Windowing.dll
Environment
PowerToys: 0.100.1 / 0.100.2
Windows: Windows 11 25H2 (Build 26100.315)
Architecture: x64
Windows App Runtime installed:
1.3.x
1.4.x
1.5.x
1.6.x
1.7.x
1.8.x (multiple side-by-side versions present)
Additional observations
Other PowerToys modules work normally (no crashes)
Windows App Runtime appears healthy
Elevated cmd (Start-Process cmd -Verb RunAs) works correctly
setx /M fails with "Access is denied" (may be related to elevated environment handling path)
Issue is isolated to Environment Variables tool in elevated mode
Possible regression area

This strongly suggests a regression in:

WinUI3 elevated window initialization
Environment Variables module refactor introduced in 0.100.1
Windows 11 25H2 compatibility with elevated WinUI host window

Likely crash point:

Microsoft.UI.Windowing.dll during elevation transition / XAML root initialization
Severity

High
(Core PowerToys feature broken for system environment management)

Reproducibility

100% on affected versions

### Upload Bug Report ZIP-file

[PowerToysReport_2026-06-28-10-23-47.zip](https://github.com/user-attachments/files/29428094/PowerToysReport_2026-06-28-10-23-47.zip)

### Additional Information

_No response_

### Other Software

_No response_

Start by reproducing the elevated launch of PowerToys.EnvironmentVariables.exe and reviewing the attached report and Event Viewer details for the Microsoft.UI.Windowing.dll failure. Compare the elevated initialization behavior in PowerToys 0.100.1 and 0.100.2. Done means the Environment Variables UI launches elevated and permits editing system variables without terminating.

Written by the indexing model from the issue text.