Asp.Net Core 3 的构建失败（Blazor 客户端）

Question

I've start to develop a web application with ASP.NET Core 3 and Blazor framework. During few days/weeks, I could build my application. Since preview 5 announced, I couldn't build my application (with dotnet build command). I've the next error:

C:\Users\a\.nuget\packages\microsoft.aspnetcore.blazor.build\3.0.0-preview5-19227-01\targets\Blazor.MonoRuntime.targets(439,5): error MSB3073: The command "dotnet "" -l    
-o "D:\Repos\IdeaStudio.Website.Client\obj\Debug\netstandard2.0\linker/" 
-x "C:\Users\a\.nuget\packages\microsoft.aspnetcore.blazor.build\3.0.0-preview5-19227-01\targets\BuiltInBclLinkerDescriptor.xml" 
-x "D:\Repos\IdeaStudio.Website.Client\obj\Debug\netstandard2.0\linker.descriptor.xml" 
-a "C:\Users\a\.nuget\packages\microsoft.aspnetcore.blazor\3.0.0-preview5-19227-01\lib\netstandard2.0\Microsoft.AspNetCore.Blazor.dll" 
-a "C:\Users\a\.nuget\packages\microsoft.aspnetcore.components\3.0.0-preview5-19227-01\lib\netstandard2.0\Microsoft.AspNetCore.Components.dll" 
-a "C:\Users\a\.nuget\packages\microsoft.aspnetcore.components.browser\3.0.0-preview5-19227-01\lib\netstandard2.0\Microsoft.AspNetCore.Components.Browser.dll" 
-a "C:\Users\a\.nuget\packages\microsoft.extensions.dependencyinjection\3.0.0-preview5.19227.9\lib\netstandard2.0\Microsoft.Extensions.DependencyInjection.dll" 
-a "C:\Users\a\.nuget\packages\microsoft.extensions.dependencyinjection.abstractions\3.0.0-preview5.19227.9\lib\netstandard2.0\Microsoft.Extensions.DependencyInjection.Abstractions.dll" 
-a "C:\Users\a\.nuget\packages\microsoft.jsinterop\3.0.0-preview5.19227.9\lib\netstandard2.0\Microsoft.JSInterop.dll" 
-a "C:\Users\a\.nuget\packages\mono.webassembly.interop\3.0.0-preview5.19227.9\lib\netstandard2.0\Mono.WebAssembly.Interop.dll" 
-a "C:\Users\a\.nuget\packages\system.componentmodel.annotations\4.6.0-preview5.19224.8\lib\netstandard2.0\System.ComponentModel.Annotations.dll" 
-a "D:\Repos\IdeaStudio.Website.Client\obj\Debug\netstandard2.0\IdeaStudio.Website.Client.dll"" exited with code 1. 
[D:\Repos\IdeaStudio.Website.Client\IdeaStudio.Website.Client.csproj]

My csproj looks like :

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <RestoreAdditionalProjectSources>
      https://dotnet.myget.org/F/aspnetcore-dev/api/v3/index.json;
      https://dotnet.myget.org/F/blazor-dev/api/v3/index.json;
    </RestoreAdditionalProjectSources>
    <LangVersion>7.3</LangVersion>
    <RazorLangVersion>3.0</RazorLangVersion>
    <TargetLatestRuntimePatch>true</TargetLatestRuntimePatch>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netstandard2.0</TargetFrameworks>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.5.1" />
    <PackageReference Include="Microsoft.AspNetCore.Blazor" Version="3.0.0-preview5-19227-01" />
    <PackageReference Include="Microsoft.AspNetCore.Blazor.Build" Version="3.0.0-preview5-19227-01" PrivateAssets="all" />
    <PackageReference Include="Microsoft.AspNetCore.Blazor.DevServer" Version="3.0.0-preview5-19227-01" PrivateAssets="all" />
  </ItemGroup>
</Project>

I did not understand for several days until...

Answer 1

This issue on the Mono GitHub is related.

Basically, as far as I understand it, somewhere in Mono the IL Linker fails and throws this cryptic error message. We can see hints to this in your error message.

As of now, michaelccote on GitHub solved the problem by adding the <BlazorLinkOnBuild>false</BlazorLinkOnBuild> element inside the <PropertyGroup>...</PropertyGroup> tags of the .csproj file

Answer 2

Maybe when I did the Visual Studio / .NET Core 3 preview 5

dotnet cli can't build an application with a csproj which contains <TargetFramework> and <TargetFrameworks> properties...

Answer 3

When you are using Blazor WebAssembly, ASP.NET Core 3.1 please navigate to yoursolution/yourproject.Client/ and edit yourproject.Client.csproj -File. Add the following line:

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    [...]
    <BlazorWebAssemblyEnableLinking>false</BlazorWebAssemblyEnableLinking>
  </PropertyGroup>
  [...]
</Project>