title: ASP.NET MVC add-migration "project failed to build"
body: <p>I am trying to add a new model and its Data Annotations, when i tried to add the migration using Package Manager Console it show me </p>
  
  <blockquote>
    <p>"The project ** project name** failed to build"</p>
  </blockquote>
  
  <p>This is my model :</p>
  
  <pre><code>{
      public class Genre
      {
          [Required]
          [StringLength(255)]
          public string Name { get; set; }
      }
  }```
  </code></pre>