This article describes an error when accessing Pages in Edit Mode. The error is:

Unable to load /EPiServer/cms/Stores/notification/ status: 500

The last code line in below three lines is the one that through exception:

var pageRouteHelper = ServiceLocator.Current.GetInstance<IPageRouteHelper>();
if (pageRouteHelper != null)
var currentpage = pageRouteHelper.Page

If one accesses any property in pageRouteHelper (PageLink,ContentLinK,Content, etc..), you will get the same exception.

This issue was identified and resolved in CMS-7825 in version EPiServer.CMS.Core 11.1.0. The recommendation is to update to this package or later.