TypeLoadException，Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter

Question

考虑我的项目文件：

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

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.Core" Version="3.0.0-preview4-19123-01" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="3.0.0-preview5-19227-01" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.2.4" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.2.4" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.2.4">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>

</Project>

我的Startup.cs：

public void ConfigureServices(IServiceCollection services)
{
    [..]

    services.
        AddMvc().
        AddNewtonsoftJson(); // Here is the problem
}

每当我尝试加载NewonsoftJson格式化程序时，在运行API时都会得到以下视图：

TypeLoadException: Could not load type 'Microsoft.AspNetCore.Mvc.Formatters.SystemTextJsonOutputFormatter' from assembly 'Microsoft.AspNetCore.Mvc.Core, Version=3.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

我应该如何解释，为什么格式化程序不在预期的位置？甚至在寻找正确的格式化程序吗？

Answer 1

我也遇到了此错误，但是使用

services.AddMvcCore().AddNewtonsoftJson();

目前正在dotnet core 3.0预览版5中运行