Я скопировал свой проект на чистый компьютер с Windows 10, на котором установлены только Visual Studio 2015 Community и SQL Server 2016 Express. Никаких других версий фреймворка, кроме установленных с Windows 10 и VS2015 или SQL Server, не установлено.

Когда я пытаюсь запустить проект WebApi, я получаю сообщение:

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

The project's packages include:

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:


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

Ответы (16)

Follow the following steps,

  1. Update visual studio to latest version (it matters)
  2. Remove all binding redirects from web.config
  3. Add this to the .csproj file:

  4. Build the project
  5. In the bin folder there should be a (WebAppName).dll.config file
  6. It should have redirects in it, copy these to the web.config
  7. Remove the above snipped from the .csproj file

It should work

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

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)

    <_FilterOutFromReferencePath Include="@(_DesignTimeFacadeAssemblies_Names->'%(OriginalIdentity)')" 
        Condition="'@(DesignFacadesToFilter)' == '@(_DesignTimeFacadeAssemblies_Names)' and '%(Identity)' != ''" /> 


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

 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.

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.


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.

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.

В одном из моих проектов были пакеты nuget с более поздней версией System.Net.Http. и в моем стартовом проекте есть ссылка на System.Net.Http v 4.0.0, я только что установил пакет Nuget System.Net.Http в свой запускаемый проект, и проблема решена

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="" and newVersion="" as follows


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.)

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.

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 build that ships with .NET 4.7.2


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 and re-added the reference, which then showed

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

Change following:

with the following:

in web.config

У меня такая же проблема, и единственный способ ее исправить - это добавить bindingRedirect в app.confing, как написал @ 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.


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"

Write-Host "Done"

Example how to use:

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

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

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

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.

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