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

System.NullReferenceException: Object reference not set to an instance of an object.
   at Co3.FKU.Dw.Services.ProductService.GetProductFieldIdsByPresentation(Product product, String categoryId, String typeId) in C:\Data\Development\git\fku-solution\Co3.FKU.Dynamicweb\Services\ProductService.cs:line 51
   at Co3.FKU.Dw.Extenders.ProductExtender.RenderSpecifications(Product product) in C:\Data\Development\git\fku-solution\Co3.FKU.Dynamicweb\Extenders\ProductExtender.cs:line 163
   at Co3.FKU.Dw.Extenders.ProductExtender.ExtendTemplate(Template template) in C:\Data\Development\git\fku-solution\Co3.FKU.Dynamicweb\Extenders\ProductExtender.cs:line 48
   at Dynamicweb.Ecommerce.Frontend.Renderer.RenderProductTemplateExtenders(RenderingContext renderingContext, Product product, Template template, Boolean extendedProperties)
   at Dynamicweb.Ecommerce.Frontend.Renderer.RenderProduct(Product product, Boolean extendedProperties, Template template, Int32 loopCounter, Boolean renderRelated, String productUrl, Int32 quantity, Int32 wishListId, Boolean renderPublicList, Boolean isRecursiveCall, Lazy`1 categoryFieldSorting, Int32 orderLineOfProductCount, RenderingContext renderingContext, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Renderer.RenderProduct(Product product, Boolean extendedProperties, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Frontend.RenderProduct(Product product, String unitId)
   at Dynamicweb.Ecommerce.Frontend.Frontend.EcomRender()
   at Dynamicweb.Ecommerce.Frontend.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)