An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.ArgumentException: The provided type 'Core.Indexing.CustomerProductIndexSchemaExtender, Core' is not compatible with the expected type 'Dynamicweb.Indexing.IIndexSchemaExtender'. (Parameter 'extenderType')
   at Dynamicweb.Indexing.Schemas.ExtensionFieldDefinition..ctor(String extenderType, IList`1 excludedFields)
   at Dynamicweb.Indexing.IndexHelper.GetField(List`1 fieldsFromExtenders, XElement fieldElement, String& fieldTypeName)
   at Dynamicweb.Indexing.IndexHelper.FillIndexWithSchema(XElement root, IIndex index)
   at Dynamicweb.Indexing.IndexHelper.ConvertToIndex(XElement obj, Boolean fillSchema)
   at Dynamicweb.Indexing.IndexService.LoadIndex(String name, Boolean fillSchema)
   at Dynamicweb.Indexing.Queries.IndexQueryProvider.Query(IQuery query, QuerySettings settings)
   at Dynamicweb.Indexing.Querying.QueryService.Query(IQuery query, QuerySettings settings)
   at Dynamicweb.Ecommerce.Indexing.ProductQueryHelper.GetProductsAutoIdsFromIndexQuery(IQuery query, ProductCatalogSettings settings, QuerySettings querySettings, IEnumerable`1& facetViewModel, IEnumerable`1& spellCheckerResult)
   at Dynamicweb.Ecommerce.ProductCatalog.ProductCatalogFrontend.RenderProductList(ProductCatalogSettings settings, QuerySettings querySettings, IQuery query, String groupId, Boolean feed, Boolean compare)
   at Dynamicweb.Ecommerce.ProductCatalog.ProductCatalogFrontend.GetModuleContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)