HttpConfiguration method EnableCors not found

Question

Enabled CORS on one project, trying to do it on another existing project, however the "EnableCors" method cannot be found in during compilation:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.EnableCors();

The exact compile fail error message is

'HttpConfiguration' does not contain a definition for 'EnableCors' and no extension method 'EnableCors' accepting a first argument of type 'HttpConfiguration' could be found (are you missing a using directive or an assembly reference)

I've done the same thing in this project as I have the other project:

<package id="Microsoft.AspNet.Cors" version="5.2.3" targetFramework="net451" />
<package id="Microsoft.AspNet.WebApi.Cors" version="5.2.3" targetFramework="net451" />

This project has odata in it though...I'm not sure if that's the major difference making it fail.

Any ideas? I've also tried

Update-Package -reinstall Microsoft.AspNet.WebApi.Cors 

Answer 1

I had to reinstall all the packages - THEN the compile error went away.

Weird. I had built & cleaned the project several times.