Description
User cannot access CMS edit mode while other parts of CMS such as Dashboard or Admin are functioning correctly. Similar error log appears when an user tries to access edit mode:
Error,****,"EPiServer.Global : Unhandled exception in ASP.NET System.Web.HttpException (0x80004005): Error executing child request for handler 'System.Web.Mvc.HttpHandlerUtil+ServerExecuteHttpHandlerWrapper'. ---> System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.ArgumentException: An item with the same key has already been added. at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer) at EPiServer.Cms.Shell.UI.Notifications.Feature.Internal.FeatureNotificationService.d__12.MoveNext()
Resolution
This is related to bug CMS-14762 and fixed in EPiServer.CMS.UI 11.22.1 and EPiServer.CMS.UI 11.34.0.
Workaround: Truncate SQL table tblNotificationSubscription.
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