[Bug]: False NU1701 warning

[bouchraRekhadda]

NuGet Product Used

MSBuild.exe

Product Version

17.1.0.7609

Worked before?

Yes with MSBuild 16.11.2.50704

Impact

I'm unable to use this version

Repro Steps & Context

Sample reproduction project:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netcoreapp3.1;net48</TargetFrameworks>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Build" Version="17.1.0" />
  </ItemGroup>
</Project>

Building using MSBuild.exe : "C:\Program Files\Microsoft Visual Studio\2022\Professional\Msbuild\Current\Bin\MSBuild.exe" ConsoleApp2.csproj /t:restore /v:m generate NU1701 warning

warning NU1701: Package 'Microsoft.Build 17.1.0' was restored using '.NETFramework,Version=v4.6.1, .NETFramework,Version=v4.6.2, .NETFramework,Version=v4.7, .NETFramework,Version=v4.7.1, .NETFramework,Version=v4.7.2, .NETFramework,Version=v4.8' instead of the project target framework '.NETCoreApp,Version=v3.1'. This package may not be fully compatible with your project

The used package reference is both compatible with .NET 6.0 and .NET Framework (from it's nuspec file)

    <dependencies>
      <group targetFramework=".NETFramework4.7.2">
         ...
      </group>
      <group targetFramework="net6.0">
        ....
      </group>
    </dependencies>

The issue seems related to #11564 since the Microsoft.Build nuspec doesn't explicitly list .NET Core 3.1 as a supported Framework (not sure though).

Verbose Logs

>warning NU1701: Package 'Microsoft.Build 17.1.0' was restored using '.NETFramework,Version=v4.6.1, .NETFramework,Version=v4.6.2, .NETFramework,Version=v4.7, .NETFramework,Version=v4.7.1, .NETFramework,Version=v4.7.2, .NETFramework,Version=v4.8' instead of the project target framework '.NETCoreApp,Version=v3.1'. This package may not be fully compatible with your project

[kartheekp-ms]

@bouchraRekhadda - I am wondering if this behavior is by design. I am able to reproduce this issue even on VS 2019 (Version 16.11.13).

Did I miss anything in the repro steps?

[bouchraRekhadda]

Did I miss anything in the repro steps?

The package Microsoft.Build version should be compatible with MSBuild version to be used; in case of VS 2019 the last version that used to work for us is 16.9.0, starting from 16.11.0 we can reproduce (here again what changed with this version is the supported TFMs in the nuspec file

• 16.9.0

    <dependencies>
      <group targetFramework=".NETFramework4.7.2">
        ...
      </group>
      <group targetFramework=".NETCoreApp2.1">
        ...
      </group>
    </dependencies>

• 16.11.0

    <dependencies>
      <group targetFramework=".NETFramework4.7.2">
        ...
      </group>
      <group targetFramework="net5.0">
        ...
      </group>
    </dependencies>

)

[nkolev92]

NU1701 is being raised based on the assets being carried.

16.11 has lib/net472 and lib/net5.0, none of which are compatible with netcoreapp3.1 without a fallback.

16.9 has lib/netcoreapp2.1 and lib/net472, out of which netcoreapp2.1 is fully compatible with netcoreapp3.1.

There's no NuGet bug here.
You can file an issue about the framework change in the msbuild repo if you'd like to, https://github.com/dotnet/msbuild/issues.