title: Sitecore PageEditor randomly shows error with Glass.Mapper
body: <p>I sometimes receive an error when I open a page in page editor mode on my Sitecore site using Glass.Mapper.</p>
  
  <blockquote>
    <p>You cannot save a class that does not contain a property that
    represents the item ID. Ensure that at least one property has been
    marked to contain the Sitecore ID. Type:
    Castle.Proxies.IBasicPageProxy
    at Glass.Mapper.Sc.Configuration.SitecoreTypeConfiguration.ResolveItem(Object
    target, Database database)
    at Glass.Mapper.Sc.GlassHtml.MakeEditable[T](Expression'1 field, Expression'1 standardOutput, T model, Object parameters,
    Context context, Database database, TextWriter writer)</p>
  </blockquote>
  
  <p>This appears in the place of the rendering, so it doesn't show up as a standard ASP error.</p>
  
  <p><strong>Restarting IIS solves this, but soon it appears again..</strong></p>
  
  <p>I use interfaces for model definitions, with every single interface inheriting from IBaseType:</p>
  
  <pre><code>[SitecoreType]
  public interface IBaseType
  {
      [SitecoreId]
      Guid Id { get; set; }
  
      [SitecoreInfo(SitecoreInfoType.Name)]
      string Name { get; set; }
  
      [SitecoreItem]
      Item InnerItem { get; set; }
  
      [SitecoreInfo(SitecoreInfoType.Url)]
      string Url { get; set; }
  
      [SitecoreInfo(SitecoreInfoType.TemplateId)]
      Guid TemplateId { get; set; }
  
      [SitecoreInfo(SitecoreInfoType.FullPath)]
      string FullPath { get; set; }
  }
  </code></pre>
  
  <p>I use Sitecore 7.5 rev. 141003 (.NET 4.5, MVC5), and the latest versions of Glass.Mapper related NuGet packages currently:</p>
  
  <ul>
  <li>Castle.Windsor 3.3.0</li>
  <li>Castle.Core 3.3.3</li>
  <li>Glass.Mapper 3.0.14.26</li>
  <li>Glass.Mapper.Sc 3.2.3.46</li>
  <li>Glass.Mapper.Sc.CastleWindsor 3.3.0.24</li>
  <li>Glass.Mapper.Sc.Mvc-5 3.3.0.43</li>
  </ul>
  
  <p>The issue appears on all machines we tried, but all of them uses Windows 8, IIS 8.5.9600. I tried reverting to the WebActivator method, but it didn't help. Model definitions are in a separate class library project, which references all glass mapper assemblies.</p>
  
  <p>I'm pretty clueless, never run into this error before on other projects. Does anyone have any idea what can cause this, or how I could debug it? </p>
  
  <p>Thank you for your help!</p>