没有为.NET Core Kestrel应用程序注册任何服务

Question

I have a console application that I'm trying to get to run Kestrel. The code files are all the boilerplate files from an empty ASP.Core application:

public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.Run(async (context) =>
        {
            await context.Response.WriteAsync("Hello World!");
        });
    }
}

However, when I run it I get the following exception:

Unhandled Exception: System.InvalidOperationException: No service for type 'Microsoft.AspNetCore.Hosting.IStartup' has been registered.

My proj file is:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore" Version="2.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.Hosting" Version="2.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" version="2.0" />
  </ItemGroup>
</Project>

Answer 1

As discussed in the comments, I couldn't reproduce the reported issue:

I found single reference regarding the exception System.InvalidOperationException: No service for type 'Microsoft.AspNetCore.Hosting.IStartup' has been registered. you mentioned, below quoted from Reference :

its the ASP.NET Core configuration system that throws this exception stating that there is no IStartup class.

I'm not this familiar with what you are doing here, but it seems that you're doing your configuration in an incorrect order .