[c#] Could not load file or assembly "System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

I've copied my project to a clean Windows 10 machine with only Visual Studio 2015 Community and SQL Server 2016 Express installed. There are no other framework versions installed apart from those installed with Windows 10 and VS2015 or SQL Server.

When I try to start the WebApi project I get the message:

Could not load file or assembly "System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" or one of its dependencies. The system cannot find the file specified.

The project's packages include:

<package id="Microsoft.AspNet.WebApi" version="5.2.3" targetFramework="net45" />
<package id="Microsoft.AspNet.WebApi.Client" version="5.2.3" targetFramework="net45" />
<package id="Microsoft.AspNet.WebApi.Core" version="5.2.3" targetFramework="net45" />
<package id="Microsoft.AspNet.WebApi.Tracing" version="5.2.3" targetFramework="net45" />
<package id="Microsoft.AspNet.WebApi.WebHost" version="5.2.3" targetFramework="net45" />

After building the project with .NET Framework 4.6.1, System.Net.Http the file is not found in the bin folder.

The file's path points to:

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.6.1\System.Net.Http.dll

The file's path of System.Net.Http.Formatting points to:

C:\Development\MyApp\packages\Microsoft.AspNet.WebApi.Client.5.2.3\lib\net45\System.Net.Http.Formatting.dll

Should the whole project target 4.5.1 or is there another way to reference the right assemblies?

I have same issue and only way how i am able to fix it is add bindingRedirect to app.confing how wrote @tripletdad99.

But if you have solution with more project is really suck update every project by hand (and also sometimes after update some nuget package you need to do it again). And it is reason why i wrote simple powershell script which if all app.configs.

 param(
    [string]$SourceDirectory,
    [string]$Package,
    [string]$OldVersion,
    [string]$NewVersion
)

Write-Host "Start fixing app.config in $sourceDirectory"
Write-Host "$Package set oldVersion to $OldVersion and newVersion $NewVersion"
Write-Host "Search app.config files.."
[array]$files = get-childitem $sourceDirectory -Include app.config App.config -Recurse | select -expand FullName
foreach ($file in $files)
{
    Write-Host $file
    $xml = [xml](Get-Content $file)
    $daNodes = $xml.configuration.runtime.assemblyBinding.dependentAssembly
    foreach($node in $daNodes)
    {
        if($node.assemblyIdentity.name -eq $package)
        {
            $updateNode = $node.bindingRedirect
            $updateNode.oldVersion = $OldVersion
            $updateNode.newVersion =$NewVersion
            Write-Host "Fix"
        }
    }
    $xml.Save($file)
}

Write-Host "Done"

Example how to use:

./scripts/FixAppConfig.ps1 -SourceDirectory "C:\project-folder" -Package "System.Net.Http" -OldVersion "0.0.0.0-4.3.2.0" -NewVersion "4.0.0.0"

Probably it is not perfect and also it will be better if somebody link it to pre-build task.

This will work in .NET 4.7.2 with Visual Studio 2017 (15.9.4):

• Remove web/app.config binding redirects
• Remove NuGet package for System.Net.Http
• Open "Add New Reference" and directly link to the new 4.2.0.0 build that ships with .NET 4.7.2

For me, I added the nuget again and the problem was solved

The only way that cleanly solved this issue for me (.NET 4.6.1) was to not only add a Nuget reference to System.Net.Http V4.3.4 for the project that actually used System.Net.Http, but also to the startup project (a test project in my case).

(Which is strange, because the correct System.Net.Http.dll existed in the bin directory of the test project and the .config assemblyBingings looked OK, too.)

You can fix this by upgrading your project to .NET Framework 4.7.2. This was answered by Alex Ghiondea - MSFT. Please go upvote him as he truly deserves it!

This is documented as a known issue in .NET Framework 4.7.1.

As a workaround you can add these targets to your project. They will remove the DesignFacadesToFilter from the list of references passed to SGEN (and add them back once SGEN is done)

<Target Name="RemoveDesignTimeFacadesBeforeSGen" BeforeTargets="GenerateSerializationAssemblies">
  <ItemGroup>
    <DesignFacadesToFilter Include="System.IO.Compression.ZipFile" />
    <_FilterOutFromReferencePath Include="@(_DesignTimeFacadeAssemblies_Names->'%(OriginalIdentity)')" 
        Condition="'@(DesignFacadesToFilter)' == '@(_DesignTimeFacadeAssemblies_Names)' and '%(Identity)' != ''" /> 
    <ReferencePath Remove="@(_FilterOutFromReferencePath)" />
  </ItemGroup>
  <Message Importance="normal" Text="Removing DesignTimeFacades from ReferencePath before running SGen." /> </Target>

<Target Name="ReAddDesignTimeFacadesBeforeSGen" AfterTargets="GenerateSerializationAssemblies">
  <ItemGroup>
    <ReferencePath Include="@(_FilterOutFromReferencePath)" />
  </ItemGroup>
  <Message Importance="normal" Text="Adding back DesignTimeFacades from ReferencePath now that SGen has ran." />
</Target>

Another option (machine wide) is to add the following binding redirect to sgen.exe.config:

<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="System.IO.Compression.ZipFile" publicKeyToken="b77a5c561934e089" culture="neutral" />
      <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.0.0.0" />
    </dependentAssembly>
  </assemblyBinding>
</runtime> This will only work on machines with .NET Framework 4.7.1. installed. Once .NET Framework 4.7.2 is installed on that machine, this workaround should be removed.

If you have multiple projects in your solution, then right-click on the solution icon in Visual Studio and select 'Manage NuGet Packages for Solution', then click on the fourth tab 'Consolidate' to consolidate all your projects to the same version of the DLLs. This will give you a list of referenced assemblies to consolidate. Click on each item in the list, then click install in the tab that appears to the right.

The above bind-redirect did not work for me so I commented out the reference to System.Net.Http in web.config. Everything seems to work OK without it.

  <system.web>
    <compilation debug="true" targetFramework="4.7.2">
      <assemblies>
        <!--<add assembly="System.Net.Http, Version=4.2.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />-->
        <add assembly="System.ComponentModel.Composition, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
      </assemblies>
    </compilation>
    <customErrors mode="Off" />
    <httpRuntime targetFramework="4.7.2" />
  </system.web>

4.6.1-2 in VS2017 users may experience the unwanted replacement of their version of System.Net.Http by the one VS2017 or Msbuild 15 wants to use.

We deleted this version here:

C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\System.Net.Http.dll

and here:

C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\System.Net.Http.dll

Then the project builds with the version we have referenced via NuGet.

Check .net framework version.
My original .net framework is older version.
After I installed .net framework 4.6, this issue is automatically solved.

Was updating an old website using nuget (including .Net update and MVC update).

I deleted the System.Net.HTTP reference in VS2017 (it was to version 2.0.0.0) and re-added the reference, which then showed 4.2.0.0.

I then updated a ton of 'packages' using nuget and got the error message, then noticed something had reset the reference to 2.0.0.0, so I removed and re-added again and it works fine... bizarre.

I had this, but, it was because I had added a NuGet package that had updated the binding redirects. Once I removed the package, the redirects were still there. I removed all of them, and then ran update-package -reinstall. This added the correct redirects.

In one of my projects there was a nuget packages with higher version of System.Net.Http. and in my startup project there reference to System.Net.Http v 4.0.0 , i just installed System.Net.Http nuget package in my startup project and the problem solved

For me, I had set my project to run on the latest version of .Net Framework (a change from .Net Framework 4.6.1 to 4.7.2).

Everything worked, no errors and published without issue, and it was only by chance that I came across the System.Net.Http error message, shown in a small, hard-to-notice, but quite important API request over the website I'm working on.

I rolled back to 4.6.1 and everything is fine again.

Changing the binding information in my web.config (or app.config) - while a "hack" in my view, allows you to move forward with your project after a NuGet package update whacks your application and gives you the System.Net.Http error.

Set oldVersion="0.0.0.0-4.1.1.0" and newVersion="4.0.0.0" as follows

<dependentAssembly>
    <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.1.1.0" newVersion="4.0.0.0" />
</dependentAssembly>

Change following:

<bindingRedirect oldVersion="0.0.0.0-4.1.1.2" newVersion="4.1.1.2" />

with the following:

<bindingRedirect oldVersion="0.0.0.0-4.1.1.2" newVersion="4.0.0.0" />

in web.config