title: After when I made add-migration and update-database problem occur
body: <p>I have to add a new model to my project 
  here is model </p>
  
  <pre><code> public class Marking
      {
          [Key]
          public int IdMakring{get;set;}
          public int IdMema { get; set; }
          [ForeignKey("Author")]
          public string Authorr {get;set;}
  
      }
  </code></pre>
  
  <p>in model memyContext I added </p>
  
  <pre><code>public DbSet&lt;Marking&gt; Marking { get; set; }
  </code></pre>
  
  <p>I did add-migration and update-database </p>
  
  <pre><code>add-migration initialll -Context  MemeGenerator.Data.ApplicationDbContext
  add-migration initialll -Context  memyContext
  update-database -Context  MemeGenerator.Data.ApplicationDbContext
  </code></pre>
  
  <p>when I made this, error show:</p>
  
  <p><a href="https://i.stack.imgur.com/ETCX3.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ETCX3.jpg" alt="enter image description here"></a></p>
  
  <p>I tried ones more update-database but it didn't help. Somebody see how can I fix this?</p>