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

System.NullReferenceException: Object reference not set to an instance of an object.
   at Dynamicweb.eCommerce.Frontend.Renderer.RenderProduct(Product Product, Boolean ExtendedProperties, Template Template, Int32 loopCounter, Boolean renderRelated, String productURL, Int32 quantity, Int32 wishListID, Boolean renderPublicList)
   at Dynamicweb.Content.Items.Editors.ProductEditor.RenderProducts(EditorRenderingContext context)
   at Dynamicweb.Content.Items.Editors.ProductEditor.RenderValue(EditorRenderingContext context)
   at Dynamicweb.Content.Items.Rendering.Renderer.RenderValueInternal(Object value, Type valueType, Template template, String tagName, ItemField meta, Boolean tryRenderLinkedItem, ItemEntry itemEntry)
   at Dynamicweb.Content.Items.Rendering.Renderer.RenderItemField(ItemField field, Object value, Dictionary`2 validationErrors, Boolean allowEditing, Template template, String tagPrefix, ItemEntry itemEntry)
   at Dynamicweb.Content.Items.Rendering.Renderer.RenderItem(ItemEntry item, ItemSettings settings)
   at Dynamicweb.Content.Items.Rendering.Renderer.RenderItems(IEnumerable`1 items, ItemListSettings settings)
   at Dynamicweb.Modules.ItemPublisher.Frontend.List()
   at Dynamicweb.Modules.ItemPublisher.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModule(DataRow& ParagraphRow)