System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
   at System.String.System.IConvertible.ToInt32(IFormatProvider provider)
   at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
   at Newtonsoft.Json.Utilities.ConvertUtils.TryConvertInternal(Object initialValue, CultureInfo culture, Type targetType, Object& value)
   at Newtonsoft.Json.Utilities.ConvertUtils.Convert(Object initialValue, CultureInfo culture, Type targetType)
   at Newtonsoft.Json.Linq.JValue.JValueDynamicProxy.TryConvert(JValue instance, ConvertBinder binder, Object& result)
   at CallSite.Target(Closure , CallSite , Object )
   at ASP._Page_app_plugins_fullwidthimagesection_softinventor_fullwidthimagesection_cshtml.Execute() in e:\Data\www.folkeferie\App_Plugins\FullWidthImageSection\softinventor.FullWidthImageSection.cshtml:line 35
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at Umbraco.Core.Profiling.ProfilingView.Render(ViewContext viewContext, TextWriter writer)
   at System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData)
   at ASP._Page_Views_Partials_grid_editors_base_cshtml.Execute() in e:\Data\www.folkeferie\Views\Partials\Grid\Editors\Base.cshtml:line 20