'System.ValueTuple, Version=0.0.0.0 required for Add-Migration on .NET 4.6.1 Class Library
Add AutoGenerateBindingRedirects
and GenerateBindingRedirectsOutputType
to your class library csproj
e.g.
<PropertyGroup>
<TargetFramework>net461</TargetFramework>
....
<AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
<GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
</PropertyGroup>