Could not load file or assembly 'Newtonsoft.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies

I made a basic Demo and reproduced this problem. It seems that WinRT component failed to find the correct assembly of Newton.Json. Temporarily the workaround is to manually add the Newtonsoft.json.dll file. You can achieve this by following steps:

1. Right click References-> Add Reference->Browse...-> Find C:\Users\.nuget\packages\Newtonsoft.Json\9.0.1\lib\portable-net45+wp80+win8+wpa81\Newtonsoft.json.dll->Click Add button.

2. Rebuild your Runtime Component project and run. This error should be gone.

I solved this problem by adding Newtonsoft.Json to the NuGet of the startup project.

I had the same issue too, to solve this, check in References of your project if the version of Newtonsoft.Json was updated (probablly don´t), then remove it and check in your either Web.config or App.config wheter the element dependentAssembly was updated as follows:

<dependentAssembly>
  <assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
  <bindingRedirect oldVersion="0.0.0.0-9.0.0.0" newVersion="9.0.0.0" />
</dependentAssembly>

After that, rebuild the project again (the dll will be replaced with the correct version)