aspnetcore: MissingMethodException occured when deploying Blazor Server app with 'Trim Unused code'

Is there an existing issue for this?

I have searched the existing issues

Describe the bug

I created an Blazor Server application using the default template on .NET 6, and deploy it with the option ‘Trim Unused code’ as self-contained. Then, I ran the application, and launched the page in browser, and the ‘System.MissingMethodException: Cannot dynamically create an instance of type ‘Microsoft.AspNetCore.Components.Web.HeadOutlet’. Reason: No parameterless constructor defined.’ occurred. When I checked HeadOutlet class of the generated Microsoft.AspNetCore.Components.Web.dll, I found that the HeadOutlet class is a empty class.

If I deployed the application without the option ‘Trim Unused code’, the generated Microsoft.AspNetCore.Components.Web.dll is normal, and no exceptions occurred.

Source code: https://1drv.ms/u/s!AsFi0-jzsGnQawMBCLgbBt2PYGg?e=BviG3k

Expected Behavior

No response

Steps To Reproduce

Create a Blazor Server application.
Deploy the application with the option ‘Trim Unused code’ as self-contained.
Run the deployed binaries.

Exceptions (if any)

fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1] An unhandled exception has occurred while executing the request. System.MissingMethodException: Cannot dynamically create an instance of type ‘Microsoft.AspNetCore.Components.Web.HeadOutlet’. Reason: No parameterless constructor defined. at System.RuntimeType.ActivatorCache…ctor(RuntimeType ) at System.RuntimeType.CreateInstanceDefaultCtor(Boolean , Boolean ) 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.AspNetCore.Components.DefaultComponentActivator.CreateInstance(Type ) at Microsoft.AspNetCore.Components.ComponentFactory.InstantiateComponent(IServiceProvider , Type ) at Microsoft.AspNetCore.Components.RenderTree.Renderer.InstantiateComponent(Type ) at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.CreateInitialRenderAsync(Type componentType, ParameterView initialParameters) at Microsoft.AspNetCore.Components.Rendering.HtmlRenderer.RenderComponentAsync(Type componentType, ParameterView initialParameters) at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c__111.<<InvokeAsync>b__11_0>d.MoveNext() --- End of stack trace from previous location --- at Microsoft.AspNetCore.Mvc.ViewFeatures.StaticComponentRenderer.PrerenderComponentAsync(ParameterView parameters, HttpContext httpContext, Type componentType) at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.PrerenderedServerComponentAsync(HttpContext context, ServerComponentInvocationSequence invocationId, Type type, ParameterView parametersCollection) at Microsoft.AspNetCore.Mvc.ViewFeatures.ComponentRenderer.RenderComponentAsync(ViewContext viewContext, Type componentType, RenderMode renderMode, Object parameters) at Microsoft.AspNetCore.Mvc.TagHelpers.ComponentTagHelper.ProcessAsync(TagHelperContext context, TagHelperOutput output) at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperRunner.<RunAsync>g__Awaited|0_0(Task task, TagHelperExecutionContext executionContext, Int32 i, Int32 count) at BlazorApp1.Pages.Pages__Layout.<ExecuteAsync>b__14_0() in C:\Users\cowne\source\repos\BlazorApp1\BlazorApp1\Pages\_Layout.cshtml:line 14 at Microsoft.AspNetCore.Razor.Runtime.TagHelpers.TagHelperExecutionContext.SetOutputContentAsync() at BlazorApp1.Pages.Pages__Layout.ExecuteAsync() at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderLayoutAsync(ViewContext context, ViewBufferTextWriter bodyWriter) at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable1 statusCode) at Microsoft.AspNetCore.Mvc.ViewFeatures.ViewExecutor.ExecuteAsync(ViewContext viewContext, String contentType, Nullable`1 statusCode) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResultFilterAsync>g__Awaited|30_0[TFilter,TFilterAsync](ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResultExecutedContextSealed context) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.ResultNext[TFilter,TFilterAsync](State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeResultFilters() — End of stack trace from previous location — at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|25_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.InvokeFilterPipelineAsync() — End of stack trace from previous location — at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope) at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger) at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)

.NET Version

6.0.101

Anything else?

Microsoft Visual Studio Professional 2022 (64-bit) Version 17.0.5

.NET SDK: Version: 6.0.101 Commit: ef49f6213a

OS Name: Windows OS Version: 10.0.19044 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\6.0.101\

Host (useful for support): Version: 6.0.1 Commit: 3a25a7f1cc

.NET SDKs installed: 5.0.402 [C:\Program Files\dotnet\sdk] 6.0.101 [C:\Program Files\dotnet\sdk]

.NET runtimes installed: Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.0-rc.2.21480.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.0-rc.2.21501.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

About this issue

Original URL
State: closed
Created 2 years ago
Reactions: 5
Comments: 21 (11 by maintainers)

Most upvoted comments

This still happens in .NET 7 Preview 7.

chrdlx on Aug 25, 2022

HeadOutlet

Thanks for your reply. However, it still doesn’t work. .NET SDK version: 6.0.4 VS version: 17.1.4

yangzhongke on Apr 14, 2022

FYI - It looks like we put a similar work around for Blazor WASM here:

https://github.com/dotnet/aspnetcore/blob/1d04387cf3b68636f8ade0118334f87ae5f56f7d/src/Components/WebAssembly/WebAssembly/src/Hosting/WebAssemblyHostBuilder.cs#L41-L44

eerhardt on Jan 3, 2023

I don’ see how Blazor server can be supported for trimming when most of ASP.NET Core isn’t.

davidfowl on Jan 1, 2023

This also happens in .NET 7.0 in my MAUI Blazor project: https://github.com/Jinjinov/Ididit

I can disable trimming for Linux and Android, but there is no way to disable trimming for iOS and macOS

Arg_NoDefCTor, Microsoft.AspNetCore.Components.Web.HeadOutlet
   at System.RuntimeType.CreateInstanceMono(Boolean , Boolean )
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean , Boolean )
   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 Blazorise.ComponentActivator.CreateInstance(Type componentType)
   at Microsoft.AspNetCore.Components.ComponentFactory.InstantiateComponent(IServiceProvider , Type )
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.InstantiateComponent(Type )
   at Microsoft.AspNetCore.Components.RenderTree.WebRenderer.AddRootComponent(Type , String )
   at Microsoft.AspNetCore.Components.WebView.Services.WebViewRenderer.AddRootComponent(Type componentType, String domElementSelector)
   at Microsoft.AspNetCore.Components.WebView.WebViewManager.AttachToPageAsync(String baseUrl, String startUrl)
   at Microsoft.AspNetCore.Components.WebView.IpcReceiver.OnMessageReceivedAsync(PageContext pageContext, String message)
   at Microsoft.AspNetCore.Components.WebView.WebViewManager.<>c__DisplayClass18_0.<<MessageReceived>b__0>d.MoveNext()

This workaround works:

@code {
    // The following dependency prevents HeadOutlet from getting trimmed away
    [DynamicDependency(DynamicallyAccessedMemberTypes.All, typeof(HeadOutlet))]
    protected override void OnAfterRender(bool firstRender)
    {
        if (firstRender)
        {
        }
    }
}

Jinjinov on Dec 22, 2022