Could not load file or assembly 'Newtonsoft.Json, Version=7.0.0.0

I had the same issue. I followed ekostadinov's forced uninstall/reinstall steps, but needed to add one extra step:

I was upgrading my Solution to Framework 4.5.2. My old Web.Config file had a namespace in the configuration tag.

<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">

I updated to:

<configuration>

Then the bindingRedirect should work for whatever version of NewtonSoft you are using:

<runtime xmlns="">
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
      <bindingRedirect oldVersion="0.0.0.0-11.0.0.0" newVersion="11.0.0.0" />
  </dependentAssembly>
</assemblyBinding>

This can happen if package.config contains 2 same packages name with a different version.

For Example,

<package id="System.Spatial" version="5.6.2" targetFramework="net45" />
<package id="System.Spatial" version="5.6.4" targetFramework="net45" />

Thank You.

I had the same issue and doing the uninstall and reinstall didn't help. At the time I was trying to install the most current version (10.0.3) of Newtonsoft.Json. I ended up installing the 7.0.1 version and then ran across another article that suggested copying that .dll to :\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE. Which I did.

Started the install REST API process again and then received a different error. When attempting to install Microsoft.Rest.ClientRuntime 2.3.2 it failed. For this, I just went into NuGet and had it install to the project in which I was installed the REST API.

Started the REST API install again and this time it installed.

Oh and if it helps anyone with searches, I was doing the Azure Immersion 02-API App tutorial using VS2015 on Windows Server 2012R2.

I had the same issue and I got the exception when I was trying to create MassTransit queues:

"Exception: System.TypeInitializationException: The type initializer for 'MassTransit.Serialization.JsonMessageSerializer' threw an exception. ---> System.IO.FileLoadException: Could not load file or assembly 'Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)"

Solution that worked for me (after spending couple of days reverting several commits):

• We had a windows service solution that has .Service project and .XUnitTests project. Both of them were using a common nuget that has dependency on Newtonsoft.Json.dll. There was no explicit reference to Newtonsoft.Json nuget package in both projects (but we were using 'using Newtonsoft.Json;' namespace in our classes), so the common nuget was using version 9 of Newtonsoft.Json by default.
• As soon as I installed the Newtonsoft.Json nuget in both .Service and .XUnitTests projects, the common nuget package started using the latest v12 Newtonsoft and that fixed my issue.

Just posting it in here if it saves anyone their valuable time.

most of the time this error happens because of different assemblies are dependent on specific version of some other assembly.

the easiest fix is to update all packages that are dependent to Newtonsoft.Json using the nuget package manager.

it will automatically set all config files in your project.

I got the same error, and fixed it by doing a 'Clean' on my solution. I'm using Newtonsoft.Json in a UWP app.

Thanks @ekostadinov. I was able to get it working with the solution from @ekostadinov. In my case, the default Web MVC template had NewtonSoft JSON version 6. I had added a class library and to that I installed NewtonSoft JSON version 9 from Nuget package manager.

I tried removing the reference from my Web project, packages config and dependencies, but still I was getting error. Now, I was getting error message saying unable to find Newtonsoft JSON version 6. Initially I was getting error message saying unable to find Newtonsoft JSON version 9.

Then I followed @ekostadinov steps.

uninstall-package newtonsoft.json -force
install-package newtonsoft.json

I got a warning with respect to a dependency in the package manager console mentioning about a dependency with the version of Web.Grease dll. But anyways, it was successful.

Just to double check, I ran the last command mentioned in the above post

Update-Package –reinstall Newtonsoft.Json

It ran without any warnings as well.

Now, I am able to use version 9 in all my projects.

Well, in my case, there were multiple projects in the solution and each was using different version of NewtonSoft.json. I had to go ahead and change the version in each project's package.config to match with latest version(Well, it could be any version just that it should be same across the projects). Once all the package.config point to the same version, all I had to do was

Update-Package –reinstall Newtonsoft.Json

Now, watch out I also had to manually change the version on web.config assembly entry in one of the projects. but that did the job.

My be it is too late but hopefully, it might be useful for the people supporting old projects.

Add dependentAssembly tag and give the version number in oldVersion for which you are getting error. In my case it was giving the error for version 6.0.0 Give the installed version value in newVersion as mentioned below:

<dependentAssembly>
            <assemblyIdentity name="Newtonsoft.Json" culture="neutral" publicKeyToken="30ad4fe6b2a6aeed" />
            <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="10.0.0.0" />
</dependentAssembly>