Could not load Newtonsoft Json

Problem: when opening .xaml from Studio, (not always but frequently) Studio will throw Could not load Newtownsoft Json… It doesn’t always happen on a certain file and happen across 2 PCs by now.

Studio Version: 2018.1.4.
Way to Reproduce: not known.
When It Appeared: seems random but constant.

Anyone has any idea why this happen and how to resolve it?