System.InvalidOperationException: The file is not a valid PDF document. at PdfSharp.Pdf.IO.PdfReader.Open(Stream stream, String password, PdfDocumentOpenMode openmode, PdfPasswordProvider passwordProvider) at PdfSharp.Pdf.IO.PdfReader.Open(Stream stream, String password, PdfDocumentOpenMode openmode) at PdfSharp.Pdf.IO.PdfReader.Open(Stream stream, PdfDocumentOpenMode openmode) at ProductsPDF.WebForm1.RunReport(List`1 json)