Building Netstandard 2.0 class library fails if dependency includes System.Net.HttpClient

[clairernovotny]

With 15.3 preview 1, building a netstandard2.0 class lib that has a dependency on a package including system.net.httpclient 4.3.2, I get build errors:

Severity	Code	Description	Project	File	Line	Suppression State
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'	ClassLibrary8	C:\dev\ClassLibrary8\ClassLibrary8\obj\Debug\netstandard2.0\RefitStubs.g.cs	39	Active
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'	ClassLibrary8	C:\dev\ClassLibrary8\ClassLibrary8\obj\Debug\netstandard2.0\RefitStubs.g.cs	40	Active
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'	ClassLibrary8	C:\dev\ClassLibrary8\ClassLibrary8\obj\Debug\netstandard2.0\RefitStubs.g.cs	42	Active

ClassLibrary8.zip

You can also see the solution explorer doing something silly:

[livarcocc]

@ericstj @dsplaisted Conflict resolution issue?

[ericstj]

I believe this is a known issue: dotnet/standard#372.

@onovotny can you update to the latest NETStandard.Library package from dotnet-core feed and see if it repros?

Try adding

 <NETStandardImplicitPackageVersion>2.0.0-preview2-25401-01</NETStandardImplicitPackageVersion>

/cc @weshaggard

[clairernovotny]

@ericstj will that work with my preview 1 tooling?

[ericstj]

Yep, it should. Not offline of course, and be careful about having dotnet-core registered and using PackageManager UI, but give it a try to see if it fixes the issue.

[clairernovotny]

Okay, that worked, closing this as a dup then. Thanks!

[weitzhandler]

@ericstj

I'm having the same issue, but in a NetStandard 1.4 assembly.
Adding the line you referenced above:

<NETStandardImplicitPackageVersion>2.0.0-preview2-25401-01</NETStandardImplicitPackageVersion>

into the csproj file didn't remove the error, but that's probably because I didn't know what to replace 2.0.0-preview2-25401-01 with.

[ericstj]

@weitzhandler open a new issue with a full description of your issue, including the version of the SDK/VS that you are using. Netstandard.dll should never appear in a netstandard1.4 project so I need to see a more comprehensive description of the issue to understand what you're seeing.

[weitzhandler]

@ericstj #1463