I’m having problems in my program. Firstly, I write data in a already existing Excel Workbook, then I convert the file from XLSX to PDF.

The data is being inserted correctly into the Excel every time, but when it reaches the line of the conversion (“pdf.ConvertFile(excelFile, pdfFile);”), the program gives me an Exception (“System.Exception: ‘Text cannot contain characters with code less than 32 (space). For these characters use SpecialCharacter instance.'”).

I already tried every Regex or input string, it always gives me the same advice. When I initiate the program without inserting something into the Excel via EPPlus, the conversion works just fine.

I believe that the way EPPlus insert strings into the sheet uses invalid characters, but I don’t know how to fix it.

I’m using EPPlus to insert data into the sheet, SautinSoft to make the XLSX2PDF conversion and PdfSharp to delete a page of the pdf that is blank. Already tried Aspose and the program worked just like I wanted, but the watermark is too scandalous.

using System;
using System.IO;
using PdfSharp.Pdf.IO;
using PdfSharp.Pdf;
using SautinSoft;
using OfficeOpenXml;
using System.Text.RegularExpressions;
using System.Runtime.CompilerServices;

namespace ToPDF
{
    class Program
    {
        static void Main(string[] args)
        {
            ExcelPackage.LicenseContext = LicenseContext.NonCommercial;

            string ExcelPath = "/Documents/Planilhas/Plant.xlsx";
            Program p = new Program();

            using (var package = new ExcelPackage(new FileInfo(ExcelPath)))
            {
                ExcelWorksheet capa = package.Workbook.Worksheets[0];
                ExcelWorksheet UNS = package.Workbook.Worksheets[1];
                ExcelWorksheet Sheet1 = package.Workbook.Worksheets[2];

                p.InsertInto(Sheet1, "C4", $"{DateTime.Now.Year}/{DateTime.Now.Month}");

                package.Save();
            }

            p.Xlsx2Pdf(ExcelPath);

        }
        private void InsertInto(ExcelWorksheet worksheet, string celula, string valor)
        {
            string cleanValor = CleanInput(valor);
            worksheet.Cells[celula].Value = cleanValor;
        }

        private static string CleanInput(string input)
        {
            return Regex.Replace(input, @"[x00-x1F]", "");
        }

        private void Xlsx2Pdf(string excelFile)
        {
            ExcelToPdf pdf = new ExcelToPdf();
            pdf.OutputFormat = SautinSoft.ExcelToPdf.eOutputFormat.Pdf;

            string pdfFile = Path.ChangeExtension(excelFile, ".pdf");

            pdf.PageStyle.PageScale.FitByHeight();

            pdf.ConvertFile(excelFile, pdfFile);

            PdfDocument p = PdfReader.Open(pdfFile, PdfDocumentOpenMode.Modify);

            int page = 1;

            p.Pages.RemoveAt(page);
            p.Save(pdfFile);
        }
    }
}

I already tried Aspose.cells and it worked, but the watermark was too big. When I don’t “package.Save()” the changes into the sheet, the conversion works. I already tried multiple REGEX methods and strings treatments, but the problem seams to be on the EPPlus’ method itself