Could not load file or assembly 'System.ComponentModel.Annotations, Version=4.1.0.0

Question

I have a .NET Standard 1.4 class library that references the System.ComponentModel.Annotations (4.3.0) NuGet package.

I'm then referencing this class library from a .NET Framework 4.6.2 test project. It builds fine, but at runtime I get the following error:

System.IO.FileLoadException occurred HResult=0x80131040
Message=Could not load file or assembly 'System.ComponentModel.Annotations, Version=4.1.0.0, 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)

I tried adding a reference to the System.ComponentModel.Annotations (4.3.0) NuGet package from the net462 project, but that didn't make any difference.

I tried adding a reference to the .NET Standard library from the net462 project, but still no luck.

Am I missing something here? Is this a known bug, if so is there a work around?

Any help is much appreciated!

Answer 1

In many cases, this can be solved by adding the following the the csproj file of your test project:

<PropertyGroup>
  <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
  <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
</PropertyGroup>

This forces the build process to create a .dll.config file in the output directory with the needed binding redirects.

The reason is that "classic" csproj test projects are true "libraries" and are not considered to need binding redirects by default. But running unit tests requires this. This only becomes an issue if referenced projects need those redirects to work correctly. This usually works when directly installing all NuGet packages that the referenced library uses, but with the new PackageReference style of NuGet packages, it does not.

See other instances where this fix has helped:

Could not load file or assembly Microsoft.Extensions.DependencyInjection.Abstractions, Version=1.1.0.0

When using .Net Standard 1.4 in a library and .Net framework 4.6.1 in and application, unable to load file System.IO.FileSystem, Version=4.0.1.0

Answer 2

I had similar problem but none of the above answers helped me. It turns out that solution is very easy, I've just run following command in Package Manager:

Install-Package System.ComponentModel.Annotations -Version 4.1.0

Answer 3

In my case, I was using 4.0.0, so I fixed it by adding in

<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
  <dependentAssembly>
    <assemblyIdentity name="System.ComponentModel.Annotations"
                      publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="4.1.0.0" newVersion="4.0.0.0"/>
  </dependentAssembly>

Adapt to your required version.

Answer 4

Got it working by using assembly redirection as described in: just invoke FunctionsAssemblyResolver.RedirectAssembly() in the begining of your program. https://stackoverflow.com/a/50776946/2705777

using System.Reflection;
using System.Diagnostics;
using System.Linq;

public class FunctionsAssemblyResolver
{
    public static void RedirectAssembly()
    {
        var list = AppDomain.CurrentDomain.GetAssemblies().OrderByDescending(a => a.FullName).Select(a => a.FullName).ToList();
        AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
    }

    private static Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args)
    {
        var requestedAssembly = new AssemblyName(args.Name);
        Assembly assembly = null;
        AppDomain.CurrentDomain.AssemblyResolve -= CurrentDomain_AssemblyResolve;
        try
        {
            assembly = Assembly.Load(requestedAssembly.Name);
        }
        catch (Exception ex)
        {
        }
        AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
        return assembly;
    }

}

Answer 5

For me, none of the other solutions worked.

I resolved this by manually adding a reference to System.ComponentModel.DataAnnotations myself (via project -> References), rather than letting Visual Studio handle it via the light-bulb quick-fix menu.