Using the E-Commerce framework's Fredhopper ECL Connector I get this error message in the CME when I open the "Fredhopper E-Commerce" mount point and browse to Categories or to Products.

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Unable to get the list of items An item with the same key has already been added. at Tridion.ExternalContentLibrary.UI.Model.Services.GeneralImpl.GetList(String id, Int32 pageIndex, Filter filter, Int32 columns) at Tridion.ExternalContentLibrary.UI.Model.Services.General.GetList(String id, Int32 pageIndex, Filter filter, Int32 columns) at SyncInvokeGetList(Object , Object[] , Object[] ) at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs) at Tridion.Web.UI.Core.Extensibility.DataExtenderOperationInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs) at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc) at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet) Hide Details

Things I checked:

  • Event Viewer: No related messages
  • ECL configration: Looks allright
  • Fredhopper URL: Is accessible from the CM server
  • Removed all ECL stub components and the stub schema: This is most likely not related (stub components are not created when browsing though the ECL mountpoint), but it did prove that the ECL mechanism is doing something: the ECL stub schema got recreated.
  • I don't think it's actually a problem in ECL, but rather that some data extender isn't handling the request correctly. I would try to remove other editors/models to see which one is incompatible. My reasoning is that this is a classic dictionary error and the ECL model code that the stacktrace is pointing to isn't using any dictionaries. Commented Nov 24, 2016 at 14:40

1 Answer 1


The ECL thing turned out to be a problem in the E-Commerce provider. After setting some facets in Fredhopper the problem was resolved.

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