microsoft / microsoft/microsoft-ui-xaml

Crash on Windows when closing a .NET MAUI modal page using — Win32 exception 0xc000027b in Microsoft.ui.xaml.dll

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#10,897 6 comments 0 reactions 1 assignee Claimed by @snigdha011997 View on GitHub
.NET MAUI bug
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Description

### Describe the bug

**Summary**

In a .NET MAUI application running on Windows (WinUI 3), closing a modal page using Navigation.PopModalAsync() causes a fatal Win32 exception.
This happens only on Windows — Android works without any issue.

The exception is thrown after clicking a Cancel button on a modal dialog page.
The crash occurs inside Microsoft.ui.xaml.dll, not in user code.

I have reproduced the issue in a minimal project, attached here.

**Environment**
Platform: Windows 11 (25H2 build 26200.7171)
.NET MAUI: .NET 8
Windows App SDK: Microsoft.WindowsAppRuntime 1.5.5
WinUI: Microsoft.UI.Xaml 3.1.5.0
Architecture: win10-x64 AppX
Crash only occurs on Windows (Android works correctly)

### Why is this important?

My apps crashs

### Steps to reproduce the bug

1. Open the sample project.
2. Run the app on Windows.
3. Open the modal page (By clicking the rigth top button ).
4. Click the Cancel button
5. The application closes immediately with a Win32 exception. (Visual Studio can trap this exception)

### Actual behavior

Apps crash

### Expected behavior

No crash

### Screenshots

Image

### NuGet package version

None

### Windows version

Windows 11 (24H2): Build 26100

### Additional context

_No response_

Contributor guide

Open the contributing guide

Assessment

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