There was a conflict between "System.Net.Http" - visual-studio

Question

When I try to build my Asp .Net Core (1.1.2) App, I'm receiving the following warning:
Found conflicts between different versions of "System.Net.Http" that could not be resolved. These reference conflicts are listed in the build log when log verbosity is set to detailed.
This then turns into a runtime error so I'm trying to fix this warning...
I turned on detailed logging in Visual Studio and I see this in the build output window:
There was a conflict between "System.Net.Http, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" and "System.Net.Http, Version=4.1.1.2, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a".
"System.Net.Http, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" was chosen because it was primary and "System.Net.Http, Version=4.1.1.2, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" was not.
References which depend on "System.Net.Http, Version=4.1.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" [C:\Users\mdepouw\.nuget\packages\system.net.http\4.3.1\ref\net46\System.Net.Http.dll].
C:\Users\mdepouw\.nuget\packages\system.net.http\4.3.1\ref\net46\System.Net.Http.dll
Project file item includes which caused reference "C:\Users\mdepouw\.nuget\packages\system.net.http\4.3.1\ref\net46\System.Net.Http.dll".
System.Net.Http
References which depend on "System.Net.Http, Version=4.1.1.2, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" [C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\System.Net.Http.dll].
C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.applicationinsights.aspnetcore\2.1.1\lib\net451\Microsoft.ApplicationInsights.AspNetCore.dll
Project file item includes which caused reference "C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.applicationinsights.aspnetcore\2.1.1\lib\net451\Microsoft.ApplicationInsights.AspNetCore.dll".
C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.applicationinsights.aspnetcore\2.1.1\lib\net451\Microsoft.ApplicationInsights.AspNetCore.dll
C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Services.Common.dll
Project file item includes which caused reference "C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Services.Common.dll".
C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Services.Common.dll
C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Persistence.MarkLogic.dll
Project file item includes which caused reference "C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Persistence.MarkLogic.dll".
C:\Users\mdepouw\Source\Repos\MyProject\MyProject.Services.Common\bin\x64\Debug\MyProject.Services.Common.dll
... more dlls that reference 4.1.1.2
Dependencies
I don't understand the part that tells me which "References" depend upon System.Net.Http, Version=4.1.1.0. I'm reading it as it depends upon itself. What am I misunderstanding?
I'm not referencing System.Net.Http directly either via Assembly references nor as a Nuget reference.
Also, the file in "C:\Users\mdepouw.nuget\packages\system.net.http\4.3.1\ref\net46\System.Net.Http.dll" is version 4.1.1.0.

Answer 1

Update: The original fix worked for my WebApi but didn't work for Viewing MVC Pages. I started to receive another runtime exception: Can not find assembly file Microsoft.CSharp.dll.
I changed <DependsOnNETStandard>true</DependsOnNETStandard> to <DependsOnNETStandard>netstandard1.6</DependsOnNETStandard> and that resolved the issue.
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>net462</TargetFramework>
<RuntimeIdentifier>win7-x64</RuntimeIdentifier>
<IsServiceFabricServiceProject>True</IsServiceFabricServiceProject>
<AssemblyName>MyProject</AssemblyName>
<Platforms>AnyCPU;x64</Platforms>
<DependsOnNETStandard>netstandard1.6</DependsOnNETStandard>
</PropertyGroup>
...
</Project>
Original Answer:
I added <DependsOnNETStandard>true</DependsOnNETStandard> per this GitHub Issue and my build warning went away and so did my runtime error.
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>net462</TargetFramework>
<RuntimeIdentifier>win7-x64</RuntimeIdentifier>
<IsServiceFabricServiceProject>True</IsServiceFabricServiceProject>
<AssemblyName>MyProject</AssemblyName>
<Platforms>AnyCPU;x64</Platforms>
<DependsOnNETStandard>true</DependsOnNETStandard>
</PropertyGroup>
...
</Project>

Answer 2

I don't understand the part that tells me which "References" depend upon System.Net.Http, Version=4.1.1.0. I'm reading it as it depends upon itself. What am I misunderstanding?
That because one of dependencies for Microsoft.AspNetCore drags in NETStandard.Library 1.6 which adds tons of System.* dependencies:
There was a conflict between “System.Net.Http”
This is a known issue about .NET core:
System.Net.Http package 4.3.2 - redirect to 4.2.0.0, assembly loading failure
This issue will be fixed in the next version 2.1.0.
The current workaround provided by Tornhoof:
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.1.1.2" newVersion="4.1.1.2" />
</dependentAssembly>
</assemblyBinding>
It uses the dll from the build extensions directory and not the one from Nuget.