System.IO.FileNotFoundException: Could not load file or assembly 'Newtonsoft.Json, Version=6.0.0.0

I get this when I try to load my CRM page. Version 8.2.12.14

System.IO.FileNotFoundException: Could not load file or assembly 'Newtonsoft.Json, Version=6.0.0.0

I have tried adding to webconfog but nothing seems to work.

Thanks