Switching to the Folder tab or to the Edit HTML dialogue results in an error


Description

Switching to the Folder tab or to the Edit HTML dialogue in Content Editor might lead to an unhandled exception after being logged in. The error similar to the following can be found in the log records:

ERROR Rendering of Folder.xaml.xml has been failed with exception: 'The control ItemList has not been initialized'
Exception: Sitecore.Web.UI.XamlSharp.ControlException
Message: The control ItemList has not been initialized
Source: Sitecore.Client
at Sitecore.Shell.Applications.ContentEditor.Editors.Folder.FolderPage.Render()
at Sitecore.Shell.Applications.ContentEditor.Editors.Folder.FolderPage.OnLoad(EventArgs e)
ERROR Rendering of EditHtml.xaml.xml has been failed with exception: 'The control ItemList has not been initialized'
Exception: Sitecore.Web.UI.XamlSharp.ControlException
Message: The control ItemList has not been initialized
Source: Sitecore.Client
at Sitecore.Shell.Applications.ContentEditor.Dialogs.EditHtml.EditHtmlPage.OnLoad(EventArgs e)

or

756 18:16:42 ERROR Application error.
Exception: System.Web.HttpUnhandledException
Message: Exception of type 'System.Web.HttpUnhandledException' was thrown.
Source: System.Web
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Nested Exception
Exception: System.NullReferenceException
Message: Object reference not set to an instance of an object.
Source: Sitecore.Client
   at Sitecore.Shell.Applications.ContentEditor.Editors.Folder.FolderPage.Render()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Solution

To resolve the issue, restart the Sitecore instance.