I have a WinJS project that is previously built on Windows 8.1 using VS 2013.
Recently I upgraded this project to Universal Windows 10 by creating a blank Javascrip
I had same issue with the following version 12.0.3:
Could not load file or assembly 'Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed' or one of its dependencies. The system cannot find the file specified.
This issue was only in my Test project (xUnit) and was caused by lack of newtonsoft.json in this project.
What is important, I was testing code from another project where library was attached and works properly.