.net core .net Core 3.0预览版2-[406:不可接受]

我基于Microsoft文档，使用Microsoft 2.2构建了一个Web API。 一切正常

更新到.net Core 3.0预览版2后，所有端点都将返回[406:不可接受]

缺少了一些东西，但到目前为止，我无法理解缺少了什么。以下代码与.net core 2.2上的代码相同

Program.cs

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }
    public static IWebHostBuilder CreateWebHostBuilder(string[] args)
    {
        return WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
        //.ConfigureKestrel((context, options) => { });
    }
}

public class Startup
{

    public void ConfigureServices(IServiceCollection services)
    {
        // Dependency Injection - Services
        services.AddSingleton<IXXXService, XXXService>();

        services.AddMvc();

        services.AddCors(options =>
        {
            options.AddPolicy("AllowAll",
                builder => builder.WithOrigins("*").AllowAnyHeader().AllowAnyMethod());
        });

        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
            c.EnableAnnotations();
        });
    }


    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseMvc();
        app.UseCors("AllowAll");

        app.UseSwagger();
        app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API"); });
    }
}

[ApiController]
[Route("api/xxx")]
public class XXXController : BaseController
{
    private readonly IXXXService _service;

    public XXXController(IXXXService service)
    {
        _service = service;
    }

    [HttpGet]
    [Produces("application/json", Type = typeof(PagedDto<XXX>))]
    [SwaggerOperation(
        Summary = "Gets all the XXX",
        Description = "Requires admin privileges",
        OperationId = "GetAllXXX",
        Tags = new[] {"XXX"}
    )]
    public IActionResult GetAllXXX([FromQuery] PagingDto pagging)
    {
        return Ok(_service.GetAllXXX(pagging));
    }
}

公共类程序
{
公共静态void Main（字符串[]args）
{
CreateWebHostBuilder（args.Build（）.Run（）；
}
公共静态IWebHostBuilder CreateWebHostBuilder（字符串[]args）
{
返回WebHost.CreateDefaultBuilder（args）
.UseStartup（）；
//.ConfigureKestrel（（上下文，选项）=>{}）；
}
}

Startup.cs

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }
    public static IWebHostBuilder CreateWebHostBuilder(string[] args)
    {
        return WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
        //.ConfigureKestrel((context, options) => { });
    }
}

public class Startup
{

    public void ConfigureServices(IServiceCollection services)
    {
        // Dependency Injection - Services
        services.AddSingleton<IXXXService, XXXService>();

        services.AddMvc();

        services.AddCors(options =>
        {
            options.AddPolicy("AllowAll",
                builder => builder.WithOrigins("*").AllowAnyHeader().AllowAnyMethod());
        });

        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
            c.EnableAnnotations();
        });
    }


    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseMvc();
        app.UseCors("AllowAll");

        app.UseSwagger();
        app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API"); });
    }
}

[ApiController]
[Route("api/xxx")]
public class XXXController : BaseController
{
    private readonly IXXXService _service;

    public XXXController(IXXXService service)
    {
        _service = service;
    }

    [HttpGet]
    [Produces("application/json", Type = typeof(PagedDto<XXX>))]
    [SwaggerOperation(
        Summary = "Gets all the XXX",
        Description = "Requires admin privileges",
        OperationId = "GetAllXXX",
        Tags = new[] {"XXX"}
    )]
    public IActionResult GetAllXXX([FromQuery] PagingDto pagging)
    {
        return Ok(_service.GetAllXXX(pagging));
    }
}

公共类启动
{
public void配置服务（IServiceCollection服务）
{
//依赖注入-服务
services.AddSingleton（）；
services.AddMvc（）；
services.AddCors（选项=>
{
options.AddPolicy（“AllowAll”，
builder=>builder.WithOrigins（“*”）.AllowAnyHeader（）.AllowAnyMethod（））；
});
services.AddSwaggerGen（c=>
{
c、 SwaggerDoc（“v1”，新的openapinfo{Title=“myapi”，Version=“v1”}）；
c、 EnableAnnotations（）；
});
}
公共无效配置（IApplicationBuilder应用程序，IHostingEnvironment环境）
{
app.UseMvc（）；
附录UseCors（“AllowAll”）；
app.UseSwagger（）；
app.UseSwaggerUI（c=>{c.SwaggerEndpoint（“/swagger/v1/swagger.json”，“我的API”）；}）；
}
}

XXXController.cs

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }
    public static IWebHostBuilder CreateWebHostBuilder(string[] args)
    {
        return WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
        //.ConfigureKestrel((context, options) => { });
    }
}

public class Startup
{

    public void ConfigureServices(IServiceCollection services)
    {
        // Dependency Injection - Services
        services.AddSingleton<IXXXService, XXXService>();

        services.AddMvc();

        services.AddCors(options =>
        {
            options.AddPolicy("AllowAll",
                builder => builder.WithOrigins("*").AllowAnyHeader().AllowAnyMethod());
        });

        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
            c.EnableAnnotations();
        });
    }


    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseMvc();
        app.UseCors("AllowAll");

        app.UseSwagger();
        app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "My API"); });
    }
}

[ApiController]
[Route("api/xxx")]
public class XXXController : BaseController
{
    private readonly IXXXService _service;

    public XXXController(IXXXService service)
    {
        _service = service;
    }

    [HttpGet]
    [Produces("application/json", Type = typeof(PagedDto<XXX>))]
    [SwaggerOperation(
        Summary = "Gets all the XXX",
        Description = "Requires admin privileges",
        OperationId = "GetAllXXX",
        Tags = new[] {"XXX"}
    )]
    public IActionResult GetAllXXX([FromQuery] PagingDto pagging)
    {
        return Ok(_service.GetAllXXX(pagging));
    }
}

[ApiController]
[路线（“api/xxx”）]
公共类XXX控制器：BaseController
{
专用只读IXXXService\u服务；
公共XXX控制器（IXXXService服务）
{
_服务=服务；
}
[HttpGet]
[products（“application/json”，Type=typeof（PagedDto））]
[招摇过市](
Summary=“获取所有XXX”，
Description=“需要管理员权限”，
OperationId=“GetAllXXX”，
Tags=new[]{“XXX”}
)]
public IActionResult GetAllXXX（[FromQuery]分页数据到分页）
{
返回Ok（_service.GetAllXXX（分页））；
}
}

我在Microsoft github上发布了这个问题，他们的回答如下：

You have to install the nuget package Microsoft.AspNetCore.Mvc.NewtonsoftJson
In your startup.cs file, add the JsonFormatter like this :

services.AddMvc（）.AddNewtonsoftJson（）.SetCompatibilityVersion（CompatibilityVersion.Version\u 3\u 0）

有了这个变化，一切都按预期进行。
这可能是aspnet core 3中最大的变化-JSON.NET现在不再捆绑。