The type 'IEnumerable<>' is defined in an assembly that is not referenced
<p>I have added the following nuget package to my MVC 5 application  X.PagedList.Mvc</p>

<p>I return the results in my controller/view as follows:</p>

<pre><code>// Repo
public IPagedList&lt;Post&gt; GetPagedPosts(int pageNumber, int pageSize)
{
   var posts = _context.Post
      .Include(x =&gt; x.Category)
      .Include(x =&gt; x.Type);

   // Return a paged list
   return posts.ToPagedList(pageNumber, pageSize);

}

// View model
public class PostViewModel
{
   public IPagedList&lt;Post&gt; Posts { get; set; }
   ...
}

// Controller method
public ActionResult Index(int? page)
{

    int pageNumber = page ?? 1;
    int pagesize = 5;

    var posts = _PostRepository.GetPagedPosts(pageNumber, pagesize);

    var viewModel = new PostViewModel
    {
        Posts = posts,
        ...
    };

    return View(viewModel);
}

// View
@model MyApp.ViewModels.PostViewModel
@using X.PagedList.Mvc;
@using X.PagedList;

&lt;p&gt;Page @(Model.Posts.PageCount &lt; Model.Posts.PageNumber ? 0 : Model.Posts.PageNumber) of @Model.Posts.PageCount &lt;/p&gt;
</code></pre>

<p>But in my view I am getting the following error <code>The type 'IEnumerable&lt;&gt;' is defined in an assembly that is not referenced. System.Runtime...</code></p>

<p>I have no project.json file in my application so what is this error?</p>