Could not load file or assembly System.Net.Http version


I'm porting a Net Framework 4 dll to Net Core. When porting my unit tests project I get an exception running some specific tests (not all).

System.IO.FileLoadException: Could not load file or assembly 'System.Net.Http, Version=, 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)

This is the project.json for my dll

  "version": "1.0.0-*",

  "dependencies": {
    "log4net": "2.0.7",
    "NETStandard.Library": "1.6.1",
    "Newtonsoft.Json": "9.0.1",
    "StackExchange.Redis": "1.2.1"

  "frameworks": {
    "netstandard1.6": {
      "imports": "dnxcore50"

And this is Packages.config for the unit tests project

  <package id="Castle.Core" version="4.0.0" targetFramework="net462" />
  <package id="log4net" version="2.0.7" targetFramework="net462" />
  <package id="Microsoft.Win32.Primitives" version="4.0.1" targetFramework="net462" />
  <package id="Moq" version="4.7.1" targetFramework="net462" />
  <package id="Newtonsoft.Json" version="9.0.1" targetFramework="net462" />
  <package id="StackExchange.Redis" version="1.2.1" targetFramework="net462" />
  <package id="System.Diagnostics.DiagnosticSource" version="4.0.0" targetFramework="net462" />
  <package id="System.IO" version="4.1.0" targetFramework="net462" />
  <package id="System.IO.FileSystem" version="4.0.1" targetFramework="net462" />
  <package id="System.IO.FileSystem.Primitives" version="4.0.1" targetFramework="net462" />
  <package id="System.IO.FileSystem.Watcher" version="4.0.0" targetFramework="net462" />
  <package id="System.Linq" version="4.1.0" targetFramework="net462" />
  <package id="System.Net.Http" version="4.1.1" targetFramework="net462" />
  <package id="System.Net.NameResolution" version="4.0.0" targetFramework="net462" />
  <package id="System.Runtime" version="4.1.0" targetFramework="net462" />
  <package id="System.Runtime.Extensions" version="4.1.0" targetFramework="net462" />
  <package id="System.Security.Cryptography.Algorithms" version="4.2.0" targetFramework="net462" />
  <package id="System.Security.Cryptography.Encoding" version="4.0.0" targetFramework="net462" />
  <package id="System.Security.Cryptography.Primitives" version="4.0.0" targetFramework="net462" />
  <package id="System.Security.Cryptography.X509Certificates" version="4.1.0" targetFramework="net462" />
  <package id="System.Text.RegularExpressions" version="4.1.0" targetFramework="net462" />
  <package id="System.Threading.Thread" version="4.0.0" targetFramework="net462" />
asked on Stack Overflow Mar 10, 2017 by Jawen • edited Jan 18, 2019 by anaximander

9 Answers


Fixed it by updating System.Net.Http to 4.3.1

answered on Stack Overflow Mar 10, 2017 by Jawen • edited Aug 24, 2017 by Jawen

I got the issue, and realized that it was because I had two different references. one reference was from my project library, and the second one was a dependency of a .Net Standard library, and therefore a Nuget package. The steps to solve were the following:

  • Remove the reference to System.Net.Http (project => add reference => remove the reference).
  • Keep the System.Net and System.Net.Http Nuget packages
  • Run Update-Package –reinstall System.Net.Http to bring back the reference.

Now it works again. :)

answered on Stack Overflow Jul 7, 2017 by Jean

Go to the app.config and remove all the lines there that reference System.Net.Http.

answered on Stack Overflow Jun 19, 2019 by Shiroy

My problem was that my service had a referenced assembly that had a reference to a newer version of System.Net.Http. I've resolved the issue by updating System.Net.Http in the service.

answered on Stack Overflow Jul 7, 2017 by Grigory Bushuev

The best and easiest way to fix this issue, is with a binding redirect.

Simply specify the oldVersion as, and newVersion as

Where is you version, for example.

answered on Stack Overflow Aug 15, 2018 by Jacob Gaiski

I had this problem, while I had 10 projects depending on each other. I fixed that by adding the version that it asked for in one of the projects that was dependent on. It was not needed for compilation, but it seems that adding it, fixed the version in other projects while restoring. So it was:

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.


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.

So I added "System.Net.Http": "4.1.1", in one project..

That actually fixed the problem while it restored 8 projects.

answered on Stack Overflow Jun 23, 2017 by Assil

And now the junior programmer solution.... double check that you are making the updates suggested by Jawen and Jean in Nuget Package Manager in the correct places too. Remember that you might have a solution with your project and a test project, and so double check to update both sets of References.

answered on Stack Overflow Sep 12, 2018 by Brian H

I had that same issue referencing System.Net.Http version in a .NET Framework 4.8 project.

Reading the Exception info carefully, I noticed that there was an entry named "FusionLog".
It stated there was a version redirection in the binding of System.Http.Net in my App.config file.

In App.config I found an XML-section like:

    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
        <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral"/>
        <bindingRedirect oldVersion="" newVersion=""/>

Removing that whole assemblyBinding section did the trick.

answered on Stack Overflow Feb 13, 2021 by lidqy

I tried out various solutions (removing the dependentAssembly OR specifying the binding redirect as well). None of them worked.

However, the only solution which worked for me was to explicitly set Specific Version for System.Net.Http (or whatever DLL giving you version issues) to False from Visual Studio.

enter image description here

answered on Stack Overflow Oct 27, 2020 by Umar Topia

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