Border: PlatformView cannot be null here | Happens randomly in release builds.

[bhavanesh2001]

Description

We are encountering a random issue in our .NET MAUI [.NET 8] application(only targets android) in release builds where an System.InvalidOperationException is being thrown.

Although the exception occurs randomly in different parts of the app, the stack trace in Sentry consistently points to the Stroke Shape mapper method in the MAUI source code. This may be due to the way we defined our Border Styles.

This leads us to believe the issue might originate from the MAUI framework itself.

Here's are couple of stack trace's i get from sentry

Stack Trace 1

System.InvalidOperationException: PlatformView cannot be null here
  ?, in ContentViewGroup ViewHandler<IBorderView, ContentViewGroup>.get_PlatformView()
  ?, in ContentViewGroup BorderHandler.Microsoft.Maui.Handlers.IBorderHandler.get_PlatformView()
  ?, in void BorderHandler.MapStrokeShape(IBorderHandler handler, IBorderView border)
  ?, in void PropertyMapper<TVirtualView, TViewHandler>.Add(string key, Action<TViewHandler, TVirtualView> action)+(IElementHandler h, IElement v) => { }
  ?, in void PropertyMapper.UpdatePropertyCore(string key, IElementHandler viewHandler, IElement virtualView)
  ?, in void PropertyMapper.UpdateProperty(IElementHandler viewHandler, IElement virtualView, string property)
  ?, in void ElementHandler.UpdateValue(string property)
  ?, in void Border.OnPropertyChanged(string propertyName)
  ?, in void Border.NotifyStrokeShapeChanges()+(object sender, PropertyChangedEventArgs e) => { }
  ?, in void WeakNotifyPropertyChangedProxy.OnPropertyChanged(object sender, PropertyChangedEventArgs e)
  ?, in void BindableObject.OnPropertyChanged(string propertyName)
  ?, in void Element.OnPropertyChanged(string propertyName)
  ?, in void RoundRectangle.OnPropertyChanged(string propertyName)
  ?, in void Element.SetParent(Element value)
  ?, in void Element.OnChildAdded(Element child)
  ?, in void VisualElement.OnChildAdded(Element child)
  ?, in void Element.AddLogicalChild(Element element)
  ?, in void Border.NotifyStrokeShapeChanges()
  ?, in static Border()+(BindableObject bindable, object oldvalue, object newvalue) => { } [0]
  ?, in void BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, object value, bool currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, bool silent)
  ?, in void BindableObject.SetValueCore(BindableProperty property, object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
  ?, in void BindableObject.SetValue(BindableProperty property, object value, SetterSpecificity specificity)
  ?, in void Setter.Apply(BindableObject target, SetterSpecificity specificity)
  ?, in void Style.ApplyCore(BindableObject bindable, Style basedOn, SetterSpecificity specificity)
  ?, in void Style.Microsoft.Maui.Controls.IStyle.Apply(BindableObject bindable, SetterSpecificity specificity)
  ?, in void MergedStyle.SetStyle(IStyle implicitStyle, IList<Style> classStyles, IStyle style)
  ?, in void MergedStyle.set_Style(IStyle value)
  ?, in static NavigableElement()+(BindableObject bindable, object oldvalue, object newvalue) => { }
  ?, in void BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, object value, bool currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, bool silent)
  ?, in void BindableObject.SetValueCore(BindableProperty property, object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
  ?, in void BindableObject.SetValue(BindableProperty property, object value)
  ?, in void NavigableElement.set_Style(Style value)
  ?, in void EditedPage.InitializeComponent()
...

Stack Trace 2

System.InvalidOperationException: PlatformView cannot be null here
  ?, in ContentViewGroup ViewHandler<IBorderView, ContentViewGroup>.get_PlatformView()
  ?, in ContentViewGroup BorderHandler.Microsoft.Maui.Handlers.IBorderHandler.get_PlatformView()
  ?, in void BorderHandler.MapStrokeShape(IBorderHandler handler, IBorderView border)
  ?, in void PropertyMapper<TVirtualView, TViewHandler>.Add(string key, Action<TViewHandler, TVirtualView> action)+(IElementHandler h, IElement v) => { }
  ?, in void PropertyMapper.UpdatePropertyCore(string key, IElementHandler viewHandler, IElement virtualView)
  ?, in void PropertyMapper.UpdateProperty(IElementHandler viewHandler, IElement virtualView, string property)
  ?, in void ElementHandler.UpdateValue(string property)
  ?, in void Border.OnPropertyChanged(string propertyName)
  ?, in void Border.NotifyStrokeShapeChanges()+(object sender, PropertyChangedEventArgs e) => { }
  ?, in void WeakNotifyPropertyChangedProxy.OnPropertyChanged(object sender, PropertyChangedEventArgs e)
  ?, in void BindableObject.OnPropertyChanged(string propertyName)
  ?, in void Element.OnPropertyChanged(string propertyName)
  ?, in void RoundRectangle.OnPropertyChanged(string propertyName)
  ?, in void Element.SetParent(Element value)
  ?, in void Element.OnChildAdded(Element child)
  ?, in void VisualElement.OnChildAdded(Element child)
  ?, in void Element.AddLogicalChild(Element element)
  ?, in void Border.NotifyStrokeShapeChanges()
  ?, in static Border()+(BindableObject bindable, object oldvalue, object newvalue) => { } [0]
  ?, in void BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, object value, bool currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, bool silent)
  ?, in void BindableObject.SetValueCore(BindableProperty property, object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
  ?, in void BindableObject.SetValue(BindableProperty property, object value, SetterSpecificity specificity)
  ?, in void Setter.Apply(BindableObject target, SetterSpecificity specificity)
  ?, in void Style.ApplyCore(BindableObject bindable, Style basedOn, SetterSpecificity specificity)
  ?, in void Style.Microsoft.Maui.Controls.IStyle.Apply(BindableObject bindable, SetterSpecificity specificity)
  ?, in void MergedStyle.SetStyle(IStyle implicitStyle, IList<Style> classStyles, IStyle style)
  ?, in void MergedStyle.set_Style(IStyle value)
  ?, in static NavigableElement()+(BindableObject bindable, object oldvalue, object newvalue) => { }
  ?, in void BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, object value, bool currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, bool silent)
  ?, in void BindableObject.SetValueCore(BindableProperty property, object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
  ?, in void Element.OnResourceChanged(BindableProperty property, object value, SetterSpecificity specificity)
  ?, in void Element.OnSetDynamicResource(BindableProperty property, string key, SetterSpecificity specificity)
  ?, in void BindableObject.SetDynamicResource(BindableProperty property, string key, SetterSpecificity specificity)
  ?, in void BindableObject.Microsoft.Maui.Controls.Internals.IDynamicResourceHandler.SetDynamicResource(BindableProperty property, string key)
  ?, in void EditedPage.InitializeComponent()
...

The exception is always thrown during page initialization, specifically from InitializeComponent(). as indicated in the stack traces.

We have style's defined for Border in App.xaml, something like below

  <Style x:Key="BorderStyle" TargetType="Border">
      <Setter Property="StrokeShape">
          <Setter.Value>
              <RoundRectangle CornerRadius="8"/>
          </Setter.Value>
      </Setter>
      <Setter Property="StrokeThickness" Value="1" />
      <Setter Property="HorizontalOptions" Value="FillAndExpand" />
      <Setter Property="BackgroundColor" Value="#FFFFFF" />
  </Style>

We are applying these style's either as Style={StaticResource BorderStyle} or Style = {DynamicReosource BorderStyle}

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

8.0.93 SR9.3

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

No response

Affected platforms

Android

Affected platform versions

Android 14

Did you find any workaround?

No response

Relevant log output

[PureWeen]

@jsuarezruiz @StephaneDelcroix

I'm curious about the implementation of StrokeShape on Border

I feel like we've talked about this a little bit at some point. The code here is using StrokeShape in a staticresource which seems fine?

But in border we're adding the stroke shape as a logical child

maui/src/Controls/src/Core/Border/Border.cs

Lines 61 to 79 in 4a36584

	void NotifyStrokeShapeChanges()
	{
	var strokeShape = StrokeShape;
	if (strokeShape is VisualElement visualElement)
	{
	AddLogicalChild(visualElement);
	_strokeShapeChanged ??= (sender, e) =>
	{
	if (e.PropertyName != nameof(Window) &&
	e.PropertyName != nameof(Parent))
	{
	OnPropertyChanged(nameof(StrokeShape));
	}
	};
	_strokeShapeProxy ??= new();
	_strokeShapeProxy.Subscribe(visualElement, _strokeShapeChanged);
	}
	}

This is something that we "fixed" at one point but had to revert wasn't it?

[bhavanesh2001]

This issue occurs randomly, and I can only identify it through Sentry from release builds. As a result, creating a reproducible project is not possible.

[jsuarezruiz]

Tried to reproduce here 39d78e7 without luck so far. I guess could be related with a DynamicResource, a StrokeShape property invalidation and maybe a navigation back where the PlatformView is already disposed (NRE). Will try to reproduce adding navigation options to the sample.

[PureWeen]

This issue occurs randomly, and I can only identify it through Sentry from release builds. As a result, creating a reproducible project is not possible.

Yea, we're in a bit of an unfortunate space right now with StrokeShape

I would say that you can't currently make StrokeShape a staticresource

Pinging @StephaneDelcroix for additional ideas here

[bhavanesh2001]

@PureWeen Thanks for letting us know. As a workaround ,we’re planning to use a custom border that extends Border, and we’ll handle the styling in the constructor.

[StephaneDelcroix]

StrokeShape is an element, need to be parented, and so can't be a StaticResource, as StaticResource are shared by instance. we need to implement x:Shared for resources.