title: The entity type 'MigrationOperation' requires a primary key to be defined
body: <p>I am trying to build my first .NET app using Identity.  It will be a basic Workout app, but I have been having trouble figuring out the Keys and ForeignKeys within Identity.  Here is my ExerciseController:</p>
  
  <pre><code> using System.Collections.Generic;
   using System.ComponentModel.DataAnnotations;
   using System.ComponentModel.DataAnnotations.Schema;
   using WorkoutGenerator.Data.Migrations;
  
      namespace RandomWorkout.Models
      {
      public class Exercise
      {
          public string Name { get; set; }
          public string Description { get; set; }
          public MuscleGroup MuscleGroup { get; set; }
          public int MuscleGroupID { get; set; }
          [Key]
          public int ID { get; set; }
  
          [ForeignKey("ID")]
          public virtual ApplicationUser User { get; set; }
  
          public IList&lt;ExerciseWorkout&gt; ExerciseWorkouts { get; set; } = new List&lt;ExerciseWorkout&gt;();
      }
  
  }`
  </code></pre>
  
  <p>When I run the migration however, I get the error </p>
  
  <blockquote>
    <p>They entity type 'MigrationOperation' requires a primary key to be
    defined.</p>
  </blockquote>
  
  <p>I have run into this issue with other entities, in which case I just had to make a new builder.Entity in my DbContext class.  With the MigrationOperation however, this doesn't seem to be the case.  Am I completely on the wrong track of how to JOIN my table with the auto generated User table? Thanks</p>