Blazor server side: Conflicting assets with the same path '/wwwroot/_framework/_bin/System.Console.dll' for content root paths

[SeppPenner]

Describe the bug

I recently tried to switch my Blazor server side (with a custom Blazor library) project from netcoreapp3.1 to net5.0. However, after changing the framework versions, I now fell over the issues that somehow System.Console.dll seems to be overwritten from the server file (If I understood https://github.com/dotnet/aspnetcore/issues/26928 correctly). Is there anything else I could check to see where exactly the issue is? Right now, I have no idea which packages or projects cause the issue. This only occurs while publishing, e.g. with dotnet publish --configuration Release -r win10-x64 --output publish/...

To Reproduce

Difficult to say, I wasn't able to reproduce this in a minimum working example yet.

Exceptions (if any)

C:\Program Files\dotnet\sdk\5.0.101\Sdks\Microsoft.NET.Sdk.Razor\build\netstandard2.0\Microsoft.NET.Sdk.Razor.StaticWebAssets.targets(208,5): error :
Conflicting assets with the same path '/wwwroot/_framework/_bin/System.Console.dll' for content root paths
'C:\Users\Nutzer\Documents\Temp\src\Example.Clients\obj\Release\net5.0\win10-x64\blazor\unlinked\System.Console.dll' and
'C:\Users\Nutzer\.nuget\packages\microsoft.netcore.app.runtime.win-x64\5.0.1\runtimes\win-x64\lib\net5.0\System.Console.dll'.
[C:\Users\Nutzer\Documents\Temp\src\Example.Server\Example.Server.csproj]

Further technical details

• ASP.Net Blazor server side project.
• Net Version: .Net 5.0
• ASP.NET Core libraries version: 5.0.1
• Visual Studio Community 2019, 16.8.30804.86
• dotnet --info:

.NET SDK (gemäß "global.json"):
 Version:   5.0.101
 Commit:    d05174dc5a

Laufzeitumgebung:
 OS Name:     Windows
 OS Version:  10.0.19041
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.101\

Host (useful for support):
  Version: 5.0.1
  Commit:  b02e13abab

.NET SDKs installed:
  2.1.806 [C:\Program Files\dotnet\sdk]
  3.1.201 [C:\Program Files\dotnet\sdk]
  3.1.202 [C:\Program Files\dotnet\sdk]
  3.1.300 [C:\Program Files\dotnet\sdk]
  3.1.402 [C:\Program Files\dotnet\sdk]
  5.0.100 [C:\Program Files\dotnet\sdk]
  5.0.101 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.All 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.18 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 2.1.23 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[SeppPenner]

Ok, I found the issue, but still I don't understand it. My project file has specified the following:

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net5.0-windows</TargetFramework>
    <RuntimeIdentifiers>win-x64</RuntimeIdentifiers>
    <LangVersion>latest</LangVersion>
  </PropertyGroup>

// And so on ...

If I run dotnet publish --configuration Release -r win10-x64 --output publish/, the above error occurs. If I run dotnet publish --configuration Release --output publish/, leaving the runtime out, it works as expected.

[mkArtakMSFT]

Thanks for contacting us. It looks like you didn't complete migration properly. We recommend following our migration guide and asking questions in StackOverflow if you face issues with it.

[SeppPenner]

Thanks for the information, I thought, I did everything in there...

In case anybody gets the same issue, I have:

• Missed @using Microsoft.AspNetCore.Components.Web.Virtualization in the _Imports.razor file (I don't believe this caused the issue, but still).
• Missed PreferExactMatches="@true" in App.razor (I don't believe this caused the issue, but still).
• Used <Project Sdk="Microsoft.NET.Sdk.Web"> instead of <Project Sdk="Microsoft.NET.Sdk.BlazorWebAssembly"> on the client side project (One of the things to look at).
• Included <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Build" Version="3.2.1" /> which shouled be removed (One of the things to look at).
• Used builder.RootComponents.Add<App>("app"); instead of builder.RootComponents.Add<App>("#app"); (Which wasn't an issue for me as I didn't use the client side as standalone, but still).
• Used <app></app> instead of <div id="app"></div> in the client side index.html file.

So, probably the issue in my case was the wrong SDK and the reference to Microsoft.AspNetCore.Components.WebAssembly.Build.