Type 'Object' is defined in an assembly that is not referenced (NET Standard 2.0/.NET Framework 4.6.1)

[ForumBot]

I'm using the [.NET Standard 2.0](https://blogs.msdn.microsoft.com/dotnet/2017/05/10/announcing-net-core-2-0-preview-1/) preview, on which my Class Libraries are based.

After having trouble with a few NuGet packages, especially regarding archive extraction, I decided to migrate my .NET Core 2.0 Console projects back to the .NET Framework 4.6.1.

The .NET Framework 4.6.1 is supposed to implement the .NET Standard 2.0 specification - according to different sources. Especially the [dotnet/standard GitHub Repo](https://github.com/dotnet/standard/blob/master/docs/versions.md).

Unfortunately, the migration to the .NET Framework resulted in the following errrors throughout all of .NET Framework Console projects:



Error CS0012 The type 'Object' is defined in an assembly that is not referenced. You must add a reference to assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.

Where `Object` can be anything: `Enum`, `Task`, ...

How would I reference .NET Standard 2.0 class libraries with .NET Framework (4.6.1) without getting such errors?

[ForumBot]

Try to add a reference to netstandard in web.config as below:

```
<system.web>
<compilation debug="true" targetFramework="4.7.1">
<assemblies>
<add assembly="netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51"/>
</assemblies>
</compilation>
</system.web>

```