Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.Binder.SetMember'

Hello. I have an MVC project that I have been working on for a long time. All of a sudden. I have been getting an error that has stopped me from being able to recompile my project. It says this.

Severity    Code    Description    Project    File    Line    Suppression State
Error    CS0656    Missing compiler required member 'Microsoft.CSharp.RuntimeBinder.Binder.SetMember'   

This error makes the use of viewbag cause an error.

I have Microsoft.CSharp references and theres no problem there. Does anyone know what could be causeing this problem? Thanks for any tips.