.NET Standard 2.0, WCF Connected Service (Could not load file or assembly 'System.ServiceModel.Primitives, Version=4.2.0.0)

This is essentially the same thing that was reported in #2111.

1. Create a trivial WCF service (the one that comes from the VS template is fine).
2. Create a .NET Standard 2.0 library, and add a Connected Services item to this WCF service.
3. Create a Desktop console (.NET 4.6.2 in my case) and reference the .NET standard class library.
4. Create an instance of the WCF client object and execute a call.
5. Observe that the application throws an exception on startup:

Could not load file or assembly ‘System.ServiceModel.Primitives, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’ or one of its dependencies. The system cannot find the file specified.

1. Try the workaround mentioned in #2111 of modify the .NET standard library’s csproj file to have the following instead of a single TargetFramework: <TargetFrameworks>net462;netstandard2.0</TargetFrameworks>
2. Re-run the console application. It will now get slightly further, before failing on:

System.IO.FileNotFoundException: ‘Could not load file or assembly ‘System.Net.Http, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’ or one of its dependencies. The system cannot find the file specified.’

Similar reports: https://www.codeproject.com/Questions/1198295/Do-I-need-to-install-NuGet-package-on-NET-standard https://social.msdn.microsoft.com/Forums/vstudio/en-US/954059c8-adb6-4fe2-939a-e60da1587545/do-i-need-to-install-nuget-package-on-net-standard-library-or-executable-project-or-both?forum=wcf

Even if the workaround were to work, I’m not sure that would be the right answer, as now two DLLs are created, one for .NET Standard 2.0, and one for .NET 4.6.2. That seems like it defeats the purpose of .NET Standard?

[MSGaryWang]

WCF Connected Service would add “System.ServiceModel.Http” NuGet package to your netstandard2.0 library but this dependency won’t be picked up by your console app project even it does reference to that netstandard2.0 library. The workaround is adding the same “System.ServiceModel.Http” NuGet package to your console app project by yourself so it would be referenced correctly. You can do this by using “Manage NuGet Package” menu item or just updating the packages.config file, for example

<?xml version=“1.0” encoding=“utf-8”?> <packages>   <package id=“System.ServiceModel.Http” version=“4.4.1” targetFramework=“net461” />   <package id=“System.ServiceModel.Primitives” version=“4.4.1” targetFramework=“net461” /> </packages>

Please let me know if this solution working for you.

[AlpeshValvi123]

I have added these two packages from NuGet and its work for in .Net Console and MVC Core Web App but not working MVC 5 web application.

1. System.ServiceModel.Http
2. System.ServiceModel.Primitives

The application is just waiting for a response.

So it’s not supported for MVC 5 Application?