Server Error in '/' Application.

Item has already been added. Key in dictionary: 'sf:OutputCacheItemProxy'  Key being added: 'sf:OutputCacheItemProxy'

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: Item has already been added. Key in dictionary: 'sf:OutputCacheItemProxy'  Key being added: 'sf:OutputCacheItemProxy'

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[ArgumentException: Item has already been added. Key in dictionary: 'sf:OutputCacheItemProxy'  Key being added: 'sf:OutputCacheItemProxy']
   System.Collections.Hashtable.Insert(Object key, Object nvalue, Boolean add) +14583981
   Telerik.Sitefinity.Web.OutputCache.SitefinityOutputCacheProvider.PersistOutputCacheItemDependencies(HttpContext context, String outputCacheKey, OutputCacheEntry outputCacheEntry, IList`1 cacheDependencies, Guid siteId, String cacheVaryKey, DateTime& utcExpiry, Boolean retry) +404
   Telerik.Sitefinity.Web.OutputCache.SitefinityOutputCacheProvider.TryHandleCacheDependencies(String outputCacheKey, Object entry, DateTime& utcExpiry) +1056
   Telerik.Sitefinity.Web.OutputCache.SitefinityOutputCacheProvider.AddAsync(String key, Object entry, DateTime utcExpiry) +100
   Telerik.Sitefinity.Web.OutputCache.<InsertResponseAsync>d__37.MoveNext() +563
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +32
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
   Telerik.Sitefinity.Web.OutputCache.<InsertResponseAsync>d__36.MoveNext() +398
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +32
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
   Telerik.Sitefinity.Web.OutputCache.<CacheResponseAsync>d__11.MoveNext() +333
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +32
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
   Telerik.Sitefinity.Web.OutputCache.<OnLeaveAsync>d__11.MoveNext() +283
   System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +32
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +62
   Telerik.Sitefinity.Web.OutputCache.TaskAsyncHelper.EndTask(IAsyncResult ar) +60
   System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +489
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +232
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +140


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4690.0