Could not load file or assembly Microsoft.Win32.Primitives, Version=4.0.0.0

Question

I am having problems running my web application.

The project setup is ASP.NET Core web application (.NET Framework). I don't seem to get any Build error. The project doesn't just run.

System.IO.FileLoadException: 'Could not load file or assembly 'Microsoft.Win32.Primitives, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'

Ales

See also: github.com/dotnet/sdk/issues/901 – Lawn

Answer 1

Try adding the System.Net.Http nuget package.

Lawn

Answer 2

This happened to me after I had updated to Visual Studio 2017 15.4.5 and also updated a load of Nuget packages. I think part of the problem is also using .net framework 4.7.1 as well, which I installed last week...

The fix for me was to remove the dependent assembly from web.config, so just comment out or delete this section:

<dependentAssembly>
    <assemblyIdentity name="Microsoft.Win32.Primitives" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.0.1.0" newVersion="4.0.1.0" />
</dependentAssembly>

Materse

Answer 3

In other for me to get it working i uninstalled the Microsoft.Win32.Primitives then installed the exact version which is 4.0. this worked fir me.

Note that there are higher versions but they did not work for me.

Ales

I had to add the System.Net.Http nuget package too, then it worked. – Lawn

Just adding the nuget package System.Net.Http worked for me. @tjrobinson, consider adding that as an answer. – Seneschal

Answer 4

I accidently deleted my *.suo files and the problem fixed itself. Maybe it was an accident, or irrelevant but i just thought to share it.

Dougdougal

Answer 5

If you are targeting .Net 4.7.1 project, I contend that a 4.7.1 versioned Primitives DLL is not available. Take a look at the properties in Nuget

I believe the Nuget expression would need a > not a = 4.6.

This feels like a hack, but it seemed to work. If you open Web.config, change this to 4.6

Tantalize