How to resolve HttpClient exists in multiple libs

Question

I'm trying to use the IdentityModel package in a .NET Core class library but I get a conflict between netstandard and System.Net.Http:

error CS0433: The type 'HttpClient' exists in both
'System.Net.Http, Version=4.1.1.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' and
'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'

The project file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="IdentityModel" Version="2.8.1" />
  </ItemGroup>
</Project>

The default Class1.cs:

using System;
using System.Net.Http;
namespace Test
{
    public class Class1
    {
        HttpClient client = new HttpClient();
        public Class1() {}
    }
}

What's the right way to resolve this issue?

Answer 1

I had a similar problem recently while trying to use HttpClient in a Xamarin project. To resolve, I added a configuration file and redirected to a specific version of System.Net.Http. The same might work for you but you have to pick the version you want to use "2.0.0.0" vs "4.1.1.1". Contents of app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.1.1.1" newVersion="4.1.1.1" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>