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.Querying.Faceting.FacetGroupHelper.PrepareIndexFieldLookup(IFacetGroup facets)
   at Dynamicweb.Indexing.Querying.Faceting.FacetGroupHelper.ConvertToFacets(XElement obj)
   at Dynamicweb.Indexing.Querying.QueryService.LoadFacets(String fileName)
   at Dynamicweb.Ecommerce.Indexing.ProductQueryHelper.LoadFacets(IQuery query, IEnumerable`1 facetGroups)
   at Dynamicweb.Ecommerce.Indexing.ProductQueryHelper.CreateQuerySettings(ProductCatalogSettings settings, IQuery query, PagingHandler pagingHandler, NameValueCollection requestValues)
   at Dynamicweb.Ecommerce.Indexing.ProductQueryHelper.GetQueryAndQuerySettings(ProductCatalogSettings settings, ContentModule contentModule, NameValueCollection requestValues, QuerySettings& querySettings)
   at Dynamicweb.Ecommerce.ProductCatalog.ProductCatalogFrontend.GetModuleContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)