How to convert an XLS Excel file to XLSX Excel file

Introduction

This C# recipe shows how you can convert a XLS file to XLSX file.

Ingredients

The recipe uses the Microsoft.Office.Interop.Excel Nuget package. You can install it using Nuget Package manager:

Install-Package Microsoft.Office.Interop.Excel

Warning! This solution will only work on a server where Excel is installed. So if you are deploying your solution to the cloud - such as Azure - this solution is unlikely to work.

C# Code Snippet

var files = Directory.GetFiles(filesFolder);

var interOpApp = new Microsoft.Office.Interop.Excel.Application();
var workBook = interOpApp.Workbooks.Open(file);
workBook.SaveAs(Filename: file + "x", FileFormat: Microsoft.Office.Interop.Excel.XlFileFormat.xlOpenXMLWorkbook);
workBook.Close();
interOpApp.Quit();