Visual Studio 2017 won't load .NET Framework references in .NET Standard library

Question

I\'ve installed Visual Studio 2017. I have a class library in the new .NET Standard format, which is able to be used by both .NET Framework and .NET Core. But when I go to <

Answer 1

As an alternative, you can use the .NET Standard Library from Nuget Package Manager to handle this issue:

The message in the Add Reference window for .NET Framework is expected. When you create a .NET Standard library, the NETStandard.Library metapackage is automatically referenced during project creation. It is a set of standard .NET APIs that are recommended to be used and supported together. This includes all of the APIs in the NETStandard.Platform package, plus additional libraries that are core to .NET, but built on top of NETStandard.Platform.

This means we don’t need to need add references individually.

Answer 2

Try to change order of TargetFrameworks inside your .csproj.

From

<TargetFrameworks>netstandard2.0;net461</TargetFrameworks>

To

<TargetFrameworks>net461;netstandard2.0</TargetFrameworks>

Answer 3

On my side, I've tried all the solution presented before but the solution was simply install NuGet package for Microsoft.CSharp.

After installation just clean the project and restart your IDE.

Answer 4

When multi-targeting both .NET Framework and .NET Core/.NET Standard you will almost certainly need to use MSBuild Conditions to prevent .NET Framework references from bleeding over into .NET Core/.NET Standard.

MSBuild conditions have been around for quite some time, but there is no support in Visual Studio to add them, you have to manually edit your .csproj file.

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

  <PropertyGroup>
    <TargetFrameworks>net461;netstandard2.0</TargetFrameworks>
  </PropertyGroup>

  <ItemGroup>
    <Compile Remove="Utility\EncryptionUtility.cs" />
  </ItemGroup>

  <ItemGroup>
    <Folder Include="Utility\" />
  </ItemGroup>

  <ItemGroup Condition=" '$(TargetFramework)' == 'net461' ">
    <Reference Include="System.Runtime.Caching" />
  </ItemGroup>

</Project>

Also note that once you do this, there are no guarantees it will work right to add a NuGet or other assembly reference using Visual Studio - you may need to do manual cleanup every time in the .csproj file to ensure the reference is added to the right conditional section. You are probably better off adding references by hand-editing the file every time.

Answer 5

This happened to me when I opened a solution targeting 4.7.1 on a fresh-install PC where only 4.7.2 was present