Multi framework targetting not working with VS2017 RC

Steps to reproduce

• Install Visual Studio 2017 RC with .NET Core support.
• Create a new .NET Core project. Type seemingly does not matter, tested with Web MVC and Console application.
• Right click on project in Solution Explorer and select “Edit name.csproj”
• Find the line with the TargetFramework element.
• Replace netcoreapp1.0 with netcoreapp1.0;net452, as demonstrated in this .NET Blog post under the section Cross-targeting.

Expected behavior

• Project compiles for both netcoreapp1.0 and net452 as previously with the project.json format.

Actual behavior

Error occurs:

MSB4115 The "HasTrailingSlash" function only accepts a scalar value, but its argument "$(OutputPath)" evaluates to "bin\Debug\netcoreapp1.0;net452\" which is not a scalar value.

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview3-004056)

Product Information:
 Version:            1.0.0-preview3-004056
 Commit SHA-1 hash:  ccc4968bc3

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.14393
 OS Platform: Windows
 RID:         win10-x64

[MartinJohns]

My suggestion is to remove the distinction. Why have two element names for a single purpose? It just adds unnecessary complexity. The new format is supposed to be simplified.

[nguerrera]

@MartinJohns

The original issue was definitely using TargetFramework to specify multiple frameworks instead of TargetFrameworks (plural). The blog post has that right.

There are two other issues:

1. Currently, you do need to specify a RuntimeIdentifier if one of your targets is the full .NET Framework and you are building an exe. We are looking to improve this, see https://github.com/dotnet/sdk/issues/396

2. You must condition the .NETCoreApp package reference to only the netcoreapp1.0 build as the package is not compatible with net452. This is also being improved with https://github.com/dotnet/sdk/pull/450 which will make the package ref implicit and remove you from having to condition it yourself.

(1) above explains the RuntimeIdentifier error you’re seeing. (2) might be the “invalid restore input” you’re seeing, but I’m seeing much clearer nuget errors on newer than RC bits:

    One or more packages are incompatible with .NETFramework,Version=v4.5.2.
    Package Microsoft.NETCore.App 1.0.1 is not compatible with net452 (.NETFramework,Version=v4.5.2).

For (1), here is how the main property group should look with both RuntimeIdentifer and TargetFrameworks set:

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netcoreapp1.0;net452</TargetFrameworks>
    <RuntimeIdentifier>win7-x86</RuntimeIdentifier>
  </PropertyGroup>

For (2), here is how the NETCore.App package ref should be conditioned

  <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp1.0'">
    <PackageReference Include="Microsoft.NETCore.App">
      <Version>1.0.1</Version>
    </PackageReference>
  </ItemGroup>

Let me know if you’re still seeing errors after applying the above and please share the full .csproj that isn’t working for you.