Crash when using <FontImageSource /> in Button after upgrading to .NET 9 / Android 35

[ThiagoFrancischini]

Description

I was upgrading my .NET 8 app targeting Android API 34 to .NET 9 targeting Android API 35. During the process, I encountered an issue on a page with the following XAML code:

    <VerticalStackLayout Margin="10">
        <HorizontalStackLayout HorizontalOptions="Fill">
            <Button Command="{Binding OnBackCommand}"
                    Scale="2"
                    Margin="-10,0,0,0"
                    HorizontalOptions="Start"
                    BackgroundColor="Transparent">
                <Button.ImageSource>
                    <FontImageSource FontFamily="MaterialSharp" Color="{DynamicResource MyColor}" Glyph="{x:Static icons:MaterialSharp.Arrow_back}"/>
                </Button.ImageSource>
            </Button>
        </HorizontalStackLayout>
    </VerticalStackLayout>

When I navigate to this page, the app crashes during InitializeComponent() with the following exception:

   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
   at System.RuntimeType.CreateInstanceMono(Boolean nonPublic, Boolean wrapExceptions)
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean wrapExceptions)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic, Boolean wrapExceptions)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.Activator.CreateInstance(Type type)
   at Microsoft.Maui.Controls.Xaml.CreateValuesVisitor.Visit(ElementNode node, INode parentNode) in /_/src/Controls/src/Xaml/CreateValuesVisitor.cs:line 113
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode) in /_/src/Controls/src/Xaml/XamlNode.cs:line 189
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode) in /_/src/Controls/src/Xaml/XamlNode.cs:line 183
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode) in /_/src/Controls/src/Xaml/XamlNode.cs:line 185
   at Microsoft.Maui.Controls.Xaml.ElementNode.Accept(IXamlNodeVisitor visitor, INode parentNode) in /_/src/Controls/src/Xaml/XamlNode.cs:line 185
   at Microsoft.Maui.Controls.Xaml.RootNode.Accept(IXamlNodeVisitor visitor, INode parentNode) in /_/src/Controls/src/Xaml/XamlNode.cs:line 242
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Visit(RootNode rootnode, HydrationContext visitorContext, Boolean useDesignProperties) in /_/src/Controls/src/Xaml/XamlLoader.cs:line 212
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, String xaml, Assembly rootAssembly, Boolean useDesignProperties) in /_/src/Controls/src/Xaml/XamlLoader.cs:line 82
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, String xaml, Boolean useDesignProperties) in /_/src/Controls/src/Xaml/XamlLoader.cs:line 57
   at Microsoft.Maui.Controls.Xaml.XamlLoader.Load(Object view, Type callingType) in /_/src/Controls/src/Xaml/XamlLoader.cs:line 53
   at Microsoft.Maui.Controls.Xaml.Extensions.LoadFromXaml[PrimeiroAcessoPage](PrimeiroAcessoPage view, Type callingType) in /_/src/Controls/src/Xaml/ViewExtensions.cs:line 42
   at Softbyte.PedidosMobile.MAUI.Views.PrimeiroAcessoPage.InitializeComponent() in C:\Fontes\Softbyte.PedidosMobile\Softbyte.PedidosMobile.MAUI\Softbyte.PedidosMobile.MAUI\obj\Debug\net9.0-android35.0\Microsoft.Maui.Controls.SourceGen\Microsoft.Maui.Controls.SourceGen.CodeBehindGenerator\Views_PrimeiroAcessoPage.xaml.sg.cs:line 23
   at Softbyte.PedidosMobile.MAUI.Views.PrimeiroAcessoPage..ctor() in C:\Fontes\Softbyte.PedidosMobile\Softbyte.PedidosMobile.MAUI\Softbyte.PedidosMobile.MAUI\Views\PrimeiroAcessoPage.xaml.cs:line 11

However, if I simply remove the FontImageSource declaration and leave the button without an image, like bellow, the app works normally:

    <VerticalStackLayout Margin="10">
        <HorizontalStackLayout HorizontalOptions="Fill">
            <Button Command="{Binding OnBackCommand}"
                    Scale="2"
                    Margin="-10,0,0,0"
                    HorizontalOptions="Start"
                    BackgroundColor="Transparent">
            </Button>
        </HorizontalStackLayout>
    </VerticalStackLayout>

I'm confident that all bindings used in this page are valid and correctly implemented, and that any referenced resources or dictionary lookups are present and accessible.

MAUI.Controls version = 9.0.81

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

9.0.30 SR3

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

.NET 8 (Please specify exact version)

Affected platforms

Android

Affected platform versions

Android 15, Android 14, Android 13

Did you find any workaround?

No response

Relevant log output

[mattleibow]

/triage

[dotnet-policy-service]

Hi @@ThiagoFrancischini. We have added the "s/needs-repro" label to this issue, which indicates that we require steps and sample code to reproduce the issue before we can take further action. Please try to create a minimal sample project/solution or code samples which reproduce the issue, ideally as a GitHub repo that we can clone. See more details about creating repros here: https://github.com/dotnet/maui/blob/main/.github/repro.md

This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.