Blazor wasm .NET 6 rc2 unable to use RegisterForJavaScript RootComponents when publishing

[corylanza]

Describe the bug

When building and running the Blazor wasm project locally I am able to use the new builder.RootComponents.RegisterForJavaScript functionality without issue, but when publishing to a folder and uploading the published project, I am getting an exception when I try to add root component via JavaScript stating that AddRootComponent is not a public invokable method with JSInvokableAttribute. Worth noting that I see no other issues and when using builder.RootComponents.Add, it seems to be only when attempting to add root components via JavaScript even after they have been registered successfully and only when the project is published to a folder.

To Reproduce

Example repo

Live Demo hosted on Github pages (error can be seen in browser console)

in Program.cs
builder.RootComponents.RegisterForJavaScript<BlazorApp>("blazor-app");
Executed on page after Blazor.Start
await Blazor.rootComponents.add(element, 'blazor-app', { });

Exceptions (if any)

Uncaught (in promise) Error: System.ArgumentException: The type 'WebRendererInteropMethods' does not contain a public invokable method with [JSInvokableAttribute("AddRootComponent")]. at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.GetCachedMethodInfo(IDotNetObjectReference , String ) at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.InvokeSynchronously(JSRuntime , DotNetInvocationInfo& , IDotNetObjectReference , String ) at Microsoft.JSInterop.Infrastructure.DotNetDispatcher.BeginInvokeDotNet(JSRuntime , DotNetInvocationInfo , String )

Further technical details

• ASP.NET Core version: Microsoft.AspNetCore.Components.WebAssembly" Version="6.0.0-rc.2.*
• VS 2022 RC 7
• Include the output of dotnet --info:

dotnet --info Output

.NET SDK (reflecting any global.json):
 Version:   6.0.100-rc.2.21505.57
 Commit:    ab39070116

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19042
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.100-rc.2.21505.57\

Host (useful for support):
  Version: 6.0.0-rc.2.21480.5
  Commit:  6b11d64e7e

.NET SDKs installed:
  2.1.602 [C:\Program Files\dotnet\sdk]
  2.1.801 [C:\Program Files\dotnet\sdk]
  2.1.802 [C:\Program Files\dotnet\sdk]
  3.0.100-preview5-011568 [C:\Program Files\dotnet\sdk]
  5.0.201 [C:\Program Files\dotnet\sdk]
  5.0.301 [C:\Program Files\dotnet\sdk]
  5.0.402 [C:\Program Files\dotnet\sdk]
  6.0.100-rc.2.21505.57 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.0.0-preview5-19227-01 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0-rc.2.21480.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.0.0-preview5-27626-15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.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.WindowsDesktop.App 3.0.0-preview5-27626-15 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.16 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.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]

[SteveSandersonMS]

I'm wondering if this is a caching issue. What happens if you visit the published site in a different browser?

[corylanza]

@SteveSandersonMS Same deal, I have tried guest windows / alternate browsers and also force deleting the old files to ensure that the compiled dlls are updated

[SteveSandersonMS]

Could you also try deleting the bin/obj folders from your project and the re-publishing? Maybe it's a build incrementalism issue.

[corylanza]

I tried deleting bin/obj folders as well as clearing NuGet Cache/restoring and still see the same error. Worth noting that other .NET 6 new Blazor features are working and the published dlls (e.g. Microsoft.AspNetCore.Components.WebAssembly.dll) have file version 6.0.21.48010 / product version 6.0.0-rc.2.21480... so it seems like its not a caching issue

[SteveSandersonMS]

OK, thanks for the additional details. This is surprising to me because I've tried this in another app and the registered JavaScript components worked fine after publishing.

Would you be able to create a minimal repro app as a GitHub repo? That is, what's the smallest set of changes you need to make to the default project template to show this issue? We could then investigate. Thanks!

[corylanza]

@SteveSandersonMS I've created a minimal repo here with a live demo of the error hosted on github pages here. In browser console you should see the exception as originally posted

[da1rren]

We have the same issue in the .net 6.0 release version.

[Xenoage]

Same issue when publishing the Angular app of the demo app for Angular component creation presented in the .NET Conf 2021 talk. Running fine from Visual Studio, but failing with the problem described above when published (dotnet publish).
All Microsoft.AspNetCore packages set to 6.0.0 (otherwise it would't compile at all).

[Xenoage]

Interestingly, the problem does not occur when calling from a custom initializer JS function, by using the javaScriptInitializer parameter in RegisterForJavaScript. See the changes in my fork of @corylanza 's minimal demo; compiled demo running here without problems.