Trim warnings from default <LayoutView> usage in Blazor Router / NotFound when AOT is enabled

[Jackhammer88]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Using default Razor syntax with and (as generated in standard Blazor templates) triggers trimming and AOT warnings when publishing with PublishTrimmed=true and PublishAot=true.

For example, this code:

<Router AppAssembly="@typeof(App).Assembly">
    <Found Context="routeData">
        <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
        <FocusOnNavigate RouteData="@routeData" Selector="h1" />
    </Found>
    <NotFound>
        <PageTitle>Not found</PageTitle>
        <LayoutView Layout="@typeof(MainLayout)">
            <p role="alert">Sorry, there's nothing at this address.</p>
        </LayoutView>
    </NotFound>
</Router>

produces trimming warnings such as:

IL2110: Blazor.UI.App.<>c.<BuildRenderTree>b__0_1(RenderTreeBuilder): Field 'Microsoft.AspNetCore.Components.LayoutView.<Layout>k__BackingField' with 'DynamicallyAccessedMembersAttribute' is accessed via reflection.
IL2111: LayoutView.WrapInLayout(Type, RenderFragment) is accessed via reflection and can't guarantee trim-safety.

These warnings come from the standard boilerplate code, and there is no obvious way to annotate the Razor or suppress the reflection usage safely without manually refactoring the rendering logic.

Expected Behavior

The generated templates and idiomatic Razor code should either:

• Avoid unsafe reflection, or
• Automatically preserve required types/members (e.g., via linker config or DynamicDependency)
• Or at least clearly document the required workaround

Steps To Reproduce

1. Create a Blazor WebAssembly app.
2. Use in a NotFound section of .
3. In .csproj set:

<PropertyGroup>
    <TargetFramework>net9.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <InvariantGlobalization>true</InvariantGlobalization>
    <RunAOTCompilation>true</RunAOTCompilation>
</PropertyGroup>

4. Run dotnet publish -c Release

Exceptions (if any)

IL2110: Blazor.UI.App.<>c.b__0_1(RenderTreeBuilder): Field 'Microsoft.AspNetCore.Components.LayoutView.k__BackingField' with 'DynamicallyAccessedMembersAttribute' is accessed via reflection.
IL2111: LayoutView.WrapInLayout(Type, RenderFragment) is accessed via reflection and can't guarantee trim-safety.

.NET Version

9.0.202

Anything else?

Environment:
Arch linux x64

[javiercn]

@Jackhammer88 thanks for contacting us.

Blazor does not support AoT nor full trimming.