Umbraco.CodeGen exception

exception

[ArgumentNullException: Value cannot be null.
Parameter name: value]
   System.Xml.Linq.XText..ctor(String value) +97958
   System.Xml.Linq.XCData..ctor(String value) +4
   Umbraco.CodeGen.DocumentTypeXmlGenerator.GenerateProperty(PropertyDeclaration prop) +1055
   System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +145
   System.Xml.Linq.XContainer.AddContentSkipNotify(Object content) +273
   System.Xml.Linq.XElement..ctor(XName name, Object content) +22
   Umbraco.CodeGen.DocumentTypeXmlGenerator.Generate(TypeDeclaration type) +379
   System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +145
   System.Collections.Generic.List`1.InsertRange(Int32 index, IEnumerable`1 collection) +392
   System.Collections.Generic.List`1.AddRange(IEnumerable`1 collection) +10
   Umbraco.CodeGen.Integration.ApplicationEvents.GenerateXml(ContentTypeConfiguration contentTypeConfiguration) +360
   Umbraco.CodeGen.Integration.ApplicationEvents.OnApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext) +783
   Umbraco.Core.CoreBootManager.<Startup>b__3(IApplicationEventHandler x) +79
   Umbraco.Core.EnumerableExtensions.ForEach(IEnumerable`1 items, Action`1 action) +204
   Umbraco.Core.CoreBootManager.Startup(Action`1 afterStartup) +174
   Umbraco.Core.UmbracoApplicationBase.StartApplication(Object sender, EventArgs e) +196
   Umbraco.Core.UmbracoApplicationBase.Application_Start(Object sender, EventArgs e) +40

[HttpException (0x80004005): Value cannot be null.
Parameter name: value]
   System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +9860497
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +118
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +172
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +336
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +296

[HttpException (0x80004005): Value cannot be null.
Parameter name: value]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +9874840
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +101
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254