Blazor 6 : "Microsoft.TypeScript.MSBuild" and a collocated JavaScript file with a .razor file cause a build error on the Ubuntu

Describe the bug

On the Ubuntu Linux 20.04 LTS, for a Blazor WebAssembly project (.NET 6) with the following conditions, 2nd time or later of execution, dotnet build command causes the build error “Two assets found targeting the same path with incompatible asset kinds”.

• The project references “Microsoft.TypeScript.MSBuild” NuGet package.
• The project contains .razor.js files that are collocated with .razor files.
• The project also contains .razor.ts files, and they are transpiled to the .razor.js files above.

Notice:

• I encountered this problem with the .NET SDK 6.0.x on Ubuntu Linux 20.04 LTS on WSL2 on my Windows 11 Pro 21H2 x64, and GitHub Actions of ubuntu-latest.
• The build error never occurred on Windows OS. (I don’t know the case on a macOS because I could not try it on macOS.)
• The 1st execution of the dotnet build was completed successfully whether runs on Ubuntu or Windows.
• It seems the error happens only when the transpiled .razor.js files already exist before the build has been started.
• If I do not use TypeScript for collocated JavaScript with Razor component, the build error never occurred even though I continue using TypeScript for located JavaScript under the “wwwroot” folder.
• At that time, I used “Microsoft.TypeScript.MSBuild” NuGet package version 4.6.2, but in my case, the build error seems to happen even another version of “Microsoft.TypeScript.MSBuild” NuGet package such as version 3.x.

To Reproduce

Requirements

• Use the minimal project below that can reproduce this problem.
  • 📦BlazorCollocateJsWithRazor-net-sdk-6.0.201.zip
• Prepare a Ubuntu Linux 20.04 LTS and install the .NET SDK 6.0.201 in it.

Steps to reproduce

1. Open a terminal on the Ubuntu Linux 20.04 LTS.
2. Change the current directory to where you extracted the “BlazorCollocateJsWithRazor-net-sdk-6.0.201.zip” file.
3. Execute dotnet build command and confirm it will be a success.
4. Execute dotnet build command one more time, then you will see the build error.

Exceptions (if any)

The build error message is below:

/usr/share/dotnet/sdk/6.0.201/Sdks/Microsoft.NET.Sdk.Razor/targets/Microsoft.NET.Sdk.Razor.JSModules.targets(95,5): error : Two assets found targeting the same path with incompatible asset kinds:  [/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/BlazorCollocateJsWithRazor.csproj]
/usr/share/dotnet/sdk/6.0.201/Sdks/Microsoft.NET.Sdk.Razor/targets/Microsoft.NET.Sdk.Razor.JSModules.targets(95,5): error : '/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/App.razor.js' with kind 'All' [/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/BlazorCollocateJsWithRazor.csproj]
/usr/share/dotnet/sdk/6.0.201/Sdks/Microsoft.NET.Sdk.Razor/targets/Microsoft.NET.Sdk.Razor.JSModules.targets(95,5): error : '/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/App.razor.js' with kind 'All' [/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/BlazorCollocateJsWithRazor.csproj]
/usr/share/dotnet/sdk/6.0.201/Sdks/Microsoft.NET.Sdk.Razor/targets/Microsoft.NET.Sdk.Razor.JSModules.targets(95,5): error : for path 'App.razor.js' [/mnt/c/Projects/Blazor/Trials/BlazorCollocateJsWithRazor/BlazorCollocateJsWithRazor.csproj]

Further technical details

dotnet --info

.NET SDK (reflecting any global.json):
 Version:   6.0.201
 Commit:    ef40e6aa06

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  20.04
 OS Platform: Linux
 RID:         ubuntu.20.04-x64
 Base Path:   /usr/share/dotnet/sdk/6.0.201/

Host (useful for support):
  Version: 6.0.3
  Commit:  c24d9a9c91

.NET SDKs installed:
  5.0.406 [/usr/share/dotnet/sdk]
  6.0.201 [/usr/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 5.0.15 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.3 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 5.0.15 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.3 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

[javiercn]

Filed an issue on TypeScript to track this problem here

[mkArtakMSFT]

Thanks for contacting us. This seems to be caused by the fact that you’re copying assets to the wwwroot folder. This blogpost should help you with resolving this issue: https://devblogs.microsoft.com/dotnet/build-client-web-assets-for-your-razor-class-library/

We plan to productize the feature referenced in the blog post and make it part of the framework in .NET 7: https://github.com/dotnet/aspnetcore/issues/40572