TL;DR: Add reference to Newtonsoft.Json.dll in every project

If you’re getting a runtime exception:

System.IO.FileLoadException: Could not load file or assembly ‘Newtonsoft.Json, Version=6.0.0.0, 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).

which by the way is impossible to troubleshoot by searching in Google or on StackOverflow because it’s way too generic and has a millions of possible causes and solutions.

In our particular case, we had to make sure that every project that directly and (what is more likely) indirectly depends on this assembly, has a reference to the version you’re using, has the nuget package installed.

Checking you have correct assembly redirects in-place won’t hurt as well:

<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-8.0.0.0" newVersion="8.0.0.0" />
      </dependentAssembly>
  </runtime>
</configuration>

Happy building!