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

System.ArgumentNullException: product is null.
Parameter name: product
   at Boxx.Web.Pdf.PdfGenerator.StreamSpecSheetPdf(Product product, String pdfTemplatePath)
   at Boxx.Web.CustomModules.PdfRenderer.Frontend.DownloadSpecSheet()
   at Boxx.Web.CustomModules.PdfRenderer.Frontend.HandleCommand(String command)
   at Boxx.Web.CustomModules.PdfRenderer.Frontend.GetContent()
   at Dynamicweb.Frontend.Content.GetModule(DataRow& ParagraphRow)