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!

Individualist

use the bindingRedirect attribute in app.config to force usage of the 4.3.0.0 lib – Puentes

For anybody missing Version=4.2.0.0: Installing System.ComponentModel.Annotations 4.4.1 from NuGet Gallery fixed it for me. – Eremite

@Eremite Thank you very much! – Doradorado

The problem seem to have worsened again in .Net Core 2.1 (used in combination with .Net 4.7.1). System.ComponentModel.Annotations 4.5.0 doesn't seem to be able to find Version=4.2.0.0 no more, forcing you to go back to bindingRedirect oldVersion="4.2.0.0" newVersion="4.0.0.0"/>. Strange that Microsoft is apparently not able to solve this issues with System.ComponentModel.Annotations. They are already there for nearly two years. – Contaminate

@Contaminate you suggestion did not work for me but an adjusted one. I ended up with <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> which fixed the problem. – Donato

@Donato : Good that you found a solution. I remember that end of May I first tried oldVersion="0.0.0.0-4.5.0.0" newVersion="4.2.1.0" but in my case that didn't work, probably because my setup is somewhat atypical. Maybe later on I will give your solution a try. – Contaminate

In my ASP.NET core project, this was my issue and solution: https://mcmap.net/q/246142/-an-error-from-azure-devops-build-could-not-locate-the-assembly-quot-system-componentmodel-annotations-quot – Extravehicular

@Donato saved my life ! I was trying to use a .NET Standard 2.0 library from a .NET Framework 4.8 WebForms project and I was getting this error. After adding what you mention in the web.config, and adding the System.ComponentModel.Annotation v5.0.0 as nuget package to the project, everything worked OK. Thanks ! – Involved

for those who face - WRN: Comparing the assembly name resulted in the mismatch: Build Number issue - the package version 4.4.1 has the same build version number as 4.2.0 – Saros

Answer 1

In many cases, this can be solved by adding the following code to 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

Shaftesbury

This does not work with .NET 4.6.1 Web apps. This issue seems to be a constant problem when developing against a webapp. The only think I can do that worked was to recompile my webapp and unload it from the solution before debugging IIS manually. This is such a pain to deal with. – Tuberous

I can confirm that this does not work in .Net 4.6.1 web apps. – Enaenable

At my solution WPF - WCF - SQL server - I changed in app.config <dependentAssembly> <assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" /> <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.5.0" /> </dependentAssembly> – Baty

The problem here is that in some more complex solutions autogenerating the BindingRedirects is not working correctly for "System.ComponentModel.Annotations", so your suggestion is helpful in general, but in this cases misses the point. – Contaminate

2021 Does not work anymore dotnet standard – Mims

When you are installing anything above 4.2.0.0 in package manager the assembly version is actually 4.2.1.0 for EVERY single version above that. so the binding redirect that works is <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> even though you may have the 4.7.0 or 5.0.0 NuGet package installed. I think its a version compatibility thing that is a pain in the arse for hybrid framework / standard projects. – Cabdriver

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

Undaunted

No a very satisfactory solution, but this worked for me. – Bruner

At the time of writing I had to use Version 4.4.1 – Clarhe

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.

Schoolroom

Btw if the change by my answer is applied, this binding redirect should be generated automatically by msbuild when it unifies assembly references during compilation. – Shaftesbury

thanks for me it was <bindingRedirect oldVersion="4.2.0.0" newVersion="4.2.1.0"/> – Weevily

In my case I created console application with .NET Framework 4.7.2, originally with a app.config transformationsm (for Debug/Release), then added Microsoft,EntityFrameworkCore.Sqlite 2.1.4 NuGet package, (VS 2017 15.8.5). It took me litle bit longer to find out, that the existing app.config transformations somehow broke the binding redirections at runtime. (After removing the transformations it was starting to work) – Kalagher

When you are installing anything above 4.2.0.0 in package manager the assembly version is actually 4.2.1.0 for EVERY single version above that. so the binding redirect that works is <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> even though you may have the 4.7.0 or 5.0.0 NuGet package installed. I think its a version compatibility thing that is a pain in the arse for hybrid framework / standard projects. – Cabdriver

Answer 4

This usually happens when visual studio can't figure out the correct bindingRedirect.

Most likely the cause it that the version of the nugget does not match the version of the produced library.

To fix do this:

1. From package manage console do:

   Get-Project –All | Add-BindingRedirect

   to regenerate assemblyBinding configuration at the config file

2. If didn't fix it, then add manually the binding redirection:

   <dependentAssembly>
       <assemblyIdentity name="System.ComponentModel.Annotations"    publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
       <bindingRedirect oldVersion="0.0.0.0-X" newVersion="Y" />
   </dependentAssembly>
   

   where:

   1. X is the version that can't be load, from the error message
   2. Y is the version on your project references. To get it, select the library from the references node, and look for the version on property pane.

Innocent

When you are installing anything above 4.2.0.0 in package manager the assembly version is actually 4.2.1.0 for EVERY single version above that. so the binding redirect that works is <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> even though you may have the 4.7.0 or 5.0.0 NuGet package installed. I think its a version compatibility thing that is a pain in the arse for hybrid framework / standard projects. – Cabdriver

Answer 5

Credit to @MiguelSlv as my case had to do with using a proper binding redirect. However, be sure that when you deploy your app to beta or production that the binding redirect is in your deployed web.config (not just in your development environment). I ended up using the following binding redirect for the NuGet package System.ComponentModel.Annotations 5.0.0 that is used in a .NET Standard 2.0 class project being consumed by my **ASP.NET MVC web application (.NET Framework 4.7.1)

<dependentAssembly>
<assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.2.1.0" newVersion="4.2.1.0" />
</dependentAssembly>

Note that 4.2.1.0 is the version shown under properties, while 5.0.0 is the NuGet package version.

Fivestar

When you are installing anything above 4.2.0.0 in package manager the assembly version is actually 4.2.1.0 for EVERY single version above that. so the binding redirect that works is <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> even though you may have the 4.7.0 or 5.0.0 NuGet package installed. I think its a version compatibility thing that is a pain in the arse for hybrid framework / standard projects. – Cabdriver

This is the correct answer now a days. – Cabdriver

Answer 6

Got it working by using assembly redirection as described in: just invoke FunctionsAssemblyResolver.RedirectAssembly() in the begining of your program. https://mcmap.net/q/246144/-azure-function-ef-core-can-39-t-load-componentmodel-annotations-4-2-0-0

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;
    }

}

Willianwillie

This is basically what BenchmarkDotNet does. github.com/dotnet/BenchmarkDotNet/blob/… – Cathey

When you are installing anything above 4.2.0.0 in package manager the assembly version is actually 4.2.1.0 for EVERY single version above that. so the binding redirect that works is <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.2.1.0" /> even though you may have the 4.7.0 or 5.0.0 NuGet package installed. I think its a version compatibility thing that is a pain in the arse for hybrid framework / standard projects. – Cabdriver

Answer 7

Also for 4.2.0.0 version error this is fixed for me in web.config:

  <dependentAssembly>
    <assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.2.1.0" newVersion="4.6.0" />
  </dependentAssembly>
</assemblyBinding> 

Acarid

Answer 8

Fixed this by installing the same System.ComponentModel.Annotations version I want to use across all the projects in the solution.

Pleasant

Answer 9

Please Add below dependentAssembly in your web.Config or app.Config file

The following configuration is added under the configuration --> runtime --> assemblyBinding node under:

<dependentAssembly>
        <assemblyIdentity name="System.ComponentModel.Annotations" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.2.1.0" newVersion="4.2.1.0" />
      </dependentAssembly>

Avidin

Answer 10

This is actually much easier than hacking config files. Hacking config files is a little scary; you might miss something! Let the IDE do it for you - hopefully it will do it right!

1. Right click solution
2. Click Manage Nuget Packages for Solution...
3. Search for System.ComponentModel.Annotations
4. Put a check box in your test projects and click Install

Now my unit tests run! Awesome!

It is still possible that you will need to use @Guillaume's answer if you have app.config files in your unit test project.

Brabble

Answer 11

I had similar problem too and in my case i just added reference from C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8.1\System.Windows.Forms.DataVisualization.Design.dll and C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8.1\System.Windows.Forms.DataVisualization.dll

Nellienellir

Answer 12

Targeting both net472 and netstandard2.0 worked for me

<PropertyGroup>
    <ProjectGuid>{9F033DF7-B256-41C2-81EE-36531467F13F}</ProjectGuid>
    <TargetFrameworks>net472;netstandard2.0</TargetFrameworks>
    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    <OutputPath>bin\$(Configuration)\</OutputPath>
</PropertyGroup>

Based on your framework version, this solution might help.

Conservatory

Answer 13

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.

Pandect

Answer 14

I fixed this error by doing the Clean Solution command in Visual Studio 2019.

Unsettled

Answer 15

I have this issue by implementing a helper function redirecting the assembly at the begin (which was suggested in this answer):

public static class FunctionsAssemblyResolver
{
    #region Public Methods

    public static void RedirectAssembly()
    {
        AppDomain.CurrentDomain.AssemblyResolve += ResolveAssemblyOnCurrentDomain;
    }

    #endregion Public Methods

    #region Private Methods

    private static Assembly ResolveAssemblyOnCurrentDomain(object sender, ResolveEventArgs args)
    {
        var requestedAssembly = new AssemblyName(args.Name);
        var assembly = default(Assembly);

        AppDomain.CurrentDomain.AssemblyResolve -= ResolveAssemblyOnCurrentDomain;

        try
        {
            assembly = Assembly.Load(requestedAssembly.Name);
        }
        catch
        { }

        AppDomain.CurrentDomain.AssemblyResolve += ResolveAssemblyOnCurrentDomain;

        return assembly;
    }

    #endregion Private Methods
}

Undersurface

Answer 16

Linux Users

You may have to install mono if you're trying to generate .exe file from linux system.

See this link on how to install mono on ubuntu 20.04

Urbano

Answer 17

I faced the same issue and fixed it by downgrading the "System.ComponentModel.Annotations" version from 5.0.0 to 4.4.1 and we can see the following lines from the project file:

<Reference Include="System.ComponentModel.Annotations, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">  
<HintPath>..\packages\System.ComponentModel.Annotations.4.4.1\lib\net461\System.ComponentModel.Annotations.dll</HintPath>

Franza

Answer 18

Non worked for me because my company uses sub systems inside the main program and the main program has System.ComponentModel.Annotations version 4.2.1 but inside the project it was using version 5 but for .net standard it's 4.2.0 so the solution was before lunching the application to explicitly load the same assembly from the main application here's the main idea

private static Assembly LoadAssemblyByPath(AssemblyName requestedAssembly, string logMessageBase)
{
    var folderPath = Path.GetDirectoryName(// my app assembly path ex this.Assembly.Location);
    var assemblyPath = Path.Combine(folderPath, requestedAssembly.Name + ".dll");

    if (File.Exists(assemblyPath))
    {
      
        try
        {   // load the assembly from the main app
            return Assembly.LoadFrom(assemblyPath);
        }
        catch (Exception e)
        {
            return null;
        }
    }

    return null;
}

Vickeyvicki