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

System.ArgumentException: String parameter languageId cannot be null or empty (Parameter 'languageId')
   at Dynamicweb.Ecommerce.Stocks.StockLocationRepository.Extract(Dictionary`2 locations, IDataReader dataReader)
   at Dynamicweb.Ecommerce.Stocks.StockLocationRepository.GetStockLocations()
   at Dynamicweb.Ecommerce.Stocks.StockLocationService.InitializeCache()
   at Dynamicweb.Caching.DictionaryCache`2.InitializeCacheDictionary()
   at System.Lazy`1.PublicationOnlyViaFactory(LazyHelper initializer)
   at System.Lazy`1.CreateValue()
   at Dynamicweb.Caching.ServiceCache`2.GetAllValues()
   at Dynamicweb.Ecommerce.Indexing.ProductIndexSchemaExtender.GetFields(String languageId)
   at Dynamicweb.Indexing.Schemas.ExtensionFieldDefinition.GetFields()
   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)
   at Dynamicweb.Indexing.IndexService.LoadIndex(String name)
   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)