Program does not contain a static 'Main' method suitable for an entry point

Hi,

I have a netcoreapp2.0 project that failed to build with the following error when I tried to build it with dotnet build:

CSC : error CS5001: Program does not contain a static 'Main' method suitable for an entry point

Then I open the project in Visual Studio (d15prerel 26629.02), the project built fine in VS, and after that the error is gone from ‘dotnet build’ and it succeeds.

After I run ‘dotnet clean’, ‘dotnet build’ starts failing with the same error

Here is my project file:

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

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
    <RuntimeIdentifiers>win10-x64</RuntimeIdentifiers>
    <!-- omitted AssemblyName and RootNamespace properties -->
    <LangVersion>Latest</LangVersion>
    <PackageTargetFallback>$(PackageTargetFallback);portable-net40+sl5+win8+wp8+wpa81;portable-net45+win8+wp8+wpa81</PackageTargetFallback>
  </PropertyGroup>

  <ItemGroup>
    <!-- some project references to other projects -->
  </ItemGroup>

</Project>

There is only one Program.cs file in the project, it has this entry point:

namespace ...
{
    static class Program
    {
...
        public static async Task Main(string[] args)
        {
        }
...

[LordDraagonLive]

Try replacing <LangVersion>Latest</LangVersion> with <LangVersion>7.1</LangVersion>

[naughtyGitCat]

Same issue here! in 3.1