title: Cannot convert string to GUID in C#.NET
body: <p>Why would the cast (to a System.Guid type) statement be invalid (second line in try block)?</p>
  
  <p>For example, suppose I have a string with a value of "5DD52908-34FF-44F8-99B9-0038AFEFDB81". I'd like to convert that to a GUID. Is that not possible?</p>
  
  <pre><code>    Guid ownerIdGuid = Guid.Empty;
      try
      {
          string ownerId = CallContextData.Current.Principal.Identity.UserId.ToString();
          ownerIdGuid = (Guid)ownerId;
      }
      catch
      {
          // Implement catch
      }
  </code></pre>