The type or namespace name 'Linq' does not exist in the namespace 'System'

Question

I have a wcf service hosted in a website in IIS and I seem to have this issue. In my web.config I have this:

Answer 1

I had no Linq methods on my Controller (Count, Where, toList, etc...). Adding the namespace:

using System.Linq;

fixed the problem for me. Maybe will help someone in the future...