LayoutCycleException caused by nested Borders in ControlTemplates

[Oxymoron290]

Description

We are encountering an intermittent, but highly reproducible LayoutCycleException on Windows when a MAUI view contains a sufficiently large visual tree with deeply nested Border elements inside control templates. The issue disappears entirely when standard MAUI Border controls are removed or replaced with a third-party border, suggesting a bug in Border layout logic or measure/arrange invalidation.

This issue has become our most frequent production crash.

The problem only appears when the UI is heavily populated. Example patterns triggering the crash could be a page containing 20+ data grids, each wrapped in a ControlTemplate containing Borders, any visual tree where a template injects multiple nested Borders several layers deep, or the exception emerges during layout/measure/arrange cycles without any custom layout logic

One work around that consistently avoid the crash involves hiding the view containing the border tree, wait about 10 seconds, and then show it again. If we wait less than 1 second, the layout cycle crash still occurs.

Expected Behavior

Border usage should not cause unrecoverable layout cycles

Actual Behavior

• Unhandled LayoutCycleException thrown from Microsoft.UI.Xaml.WinUI.dll
• When Application.Current.DebugSettings.LayoutCycleDebugBreakLevel = Low, the debugger breaks into native code with no managed stack available

Sample Exception

Microsoft.UI.Xaml.dll!LayoutCycleDetected
Exception: Layout cycle detected. Layout was invalidated during measure or arrange.

A small C# MAUI Project that triggers the exception is attached.

To reproduce the issue using the sample application, there are controls across the top of the app. the "Add Stuff" button will trigger the crash depending on the parameters to the right. The "Add no border stuff" will never trigger the crash, demonstrating the workaround described above. The sliders to the right allow you to configure the number of elements to add the level of depth to add them (It nests them inside horizontal stack layouts). There is also a button to clean up the elements.

The following table shows some sample data that I used while testing this MVP and what my results were. Each run was conducted on a new instance except for the last run.

Layers	Elements	Result
3	1024	Crashed
1	1024	No Crash
8	1	No Crash
8	25	No Crash
8	300	Crash
1	299	No Crash
2	304	No Crash
3	304	Crash
2	1024	Crash
1	1024	Crash (app was not reset from previous run)

Steps to Reproduce

On Windows in Visual Studio:

1. File → New → Project → .NET MAUI App

• Choose either “.NET MAUI App”
• Leave defaults, name it anything (ex: BorderLayoutCycleRepro)
• Target Windows

2. Add a UI that creates a large number of nested controls

• Open MainPage.xaml
• Add HorizontalStackLayout with a border inside it, followed by another Horizontal Stack Layout, repeating. Do this many times. multiple layers >2 with hundreds of elements >300

3. Run the app on Windows

• In the running application, observe the LayoutCycleException crash. The application will exit.

Sample application avaialble here

Link to public reproduction project repository

https://github.com/FFIDX-Success/BorderTemplateCrashExample

Version with bug

9.0.111 SR11.1

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

11 25h2 26200.6899

Did you find any workaround?

One work around that consistently avoid the crash involves hiding the view containing the border tree, wait about 10 seconds, and then show it again. If we wait less than 1 second, the layout cycle crash still occurs.

Relevant log output

[HarishKumarSF4517]

This issue has been validated in Visual Studio 18.0.0 Insiders with MAUI latest Versions(9.0.0, 9.0.14, 9.0.111 & 9.0.120). It can be reproduced from 9.0.14 on Windows platform.

[karthikraja-arumugam]

The regression was introduced by #24844, which implemented performance improvements for the Border control. However, this change resulted in a layout cycle detection issue when adding or manipulating multiple borders, due to continuous updates to each Border’s path geometry.
To resolve this, you can apply batch updates with a minimal delay. When adding or manipulating borders, use batch updates as shown in the below code,

private async void OnAddClicked(object sender, EventArgs e)
{
	int total = (int)CountSlider.Value;
	int batchSize = 20;
	int added = 0;

	while (added < total)
	{
		int currentBatch = Math.Min(batchSize, total - added);
		for (int i = 0; i < currentBatch; i++)
		{
			var control = new NovaButton();
			control.Text = $"Button {added + i} 0x{control.GetHashCode():x8}";

			if (ReferenceEquals(sender, NoBorderButton))
				control.Style = Resources["NoBorderControlTemplate"] as Style;
			else
				control.Style = Resources["BorderControlTemplate"] as Style;

			const int width = 192;
			const int height = 80;
			var x = Random.Shared.Next(0, (int)TheLayout.Width - width);
			var y = Random.Shared.Next(0, (int)TheLayout.Height - height);

			View innermost = control;
			for (int j = 0; j < (int)DepthSlider.Value; j++)
			{
				var stackLayout = new HorizontalStackLayout();
				stackLayout.BackgroundColor = Color.FromHsv((float)j / (float)DepthSlider.Value, 1, 1);
				stackLayout.Margin = new Thickness(1);
				stackLayout.Add(innermost);
				innermost = stackLayout;
			}

			AbsoluteLayout.SetLayoutBounds(innermost, new Rect(x, y, 192, 40));
			TheLayout.Add(innermost);
		}
		added += currentBatch;
		await Task.Delay(1); // Yield to UI thread to allow layout to process
	}
}

private async void OnInvalidateClicked(object sender, EventArgs e)
{
	int batchSize = 10; // Smaller batch size
	int processed = 0;
	int total = TheLayout.Children.Count;

	while (processed < total)
	{
		int currentBatch = Math.Min(batchSize, total - processed);
		for (int i = 0; i < currentBatch; i++)
		{
			var child = TheLayout.Children[processed + i];
			var button = FindNovaButton((View)child);
			if (button != null)
			{
				// Only update text or bounds, not both at once if possible
				button.Text += "1";
			}

			var bounds = AbsoluteLayout.GetLayoutBounds((View)child);
			bounds.Width++;
			bounds.Height++;
			bounds.X++;
			bounds.Y++;
			AbsoluteLayout.SetLayoutBounds((View)child, bounds);
		}
		processed += currentBatch;
		await Task.Delay(10); 
	}
	// Only invalidate parent once after all updates
	TheLayout.InvalidateMeasure();
}

[danielancines]

I getting the same problem on my company app, because of my app complexity we're not allowed to use the warkaround that @karthikraja-arumugam wrote above, any update about this? This issue is blocking upgrade to .net 10.