dotnet restore warning NU1701

Question

I am using .NET Core with C#, and when I did dotnet restore, it gave the following error:

PS C:\workspace\Arbitrator> dotnet restore

C:\workspace\Arbitrator\Arbitrator.csproj : warning NU1701: Package 'PusherClient 0.5.0' was restored using '.NETFramework,Version=v4.6.1' instead the project target framework '.NETCoreApp,Version=v2.0'. This may cause compatibility problems. C:\workspace\Arbitrator\Arbitrator.csproj : warning NU1701: Package 'WebSocket4Net 0.14.1' was restored using '.NETFramework,Version=v4.6.1' instead the project target framework '.NETCoreApp,Version=v2.0'. This may cause compatibility problems.

This package in problem is PusherClient. I just followed the NuGet documents to import it. How can I fix this warning?

Answer 1

You don't necessarily have to wait until PusherClient is upgraded for .NET Core.

Referencing .NET Framework 4.6.1 (and below) from .NET Core is a new feature available since .NET Core/Standard 2.0 preview 2 / VS 2017 preview 15.3, and according to MS, it can be thought of as a feature that helps you migrate .NET Framework code to .NET Standard or .NET Core over time.

1. You can just suppress this warning

   • for a specific package

    <PackageReference Include="Contoso.Base.API" Version="1.0.3">
        <NoWarn>NU1701</NoWarn>
    </PackageReference>
   

   • for all packages

    <NoWarn>NU1701</NoWarn>
   

   See scenarios 2 and 3 in NuGet wiki for ways to do it from GUI.

   It is possible, though, that your application may fail in run-time when you call an API (like something from WPF) that is not supported by .NET Core. Another reason of a failure could be native APIs possibly used by PusherClient. So you should test it extensively. But in most cases, it will just work on all platforms where .NET Core is supported (for example, I have tested an application with MathNet.Numerics dependency and it worked on Linux even though MathNet.Numerics is also .NET Framework 4.6.1).

2. If you don't need your app to be cross-platform, just change its target framework to .NET 4.6.1 by adding the following to your csproj file:

    <TargetFramework>net461</TargetFramework>