title: How to convert xls file to xlsx file using C#?
body: <p>I was developing an application which read data from an excel file, but when I try to open it, an exception  was thrown if the source file is saved with the <em>xls format</em> (File contains corrupted data error when opening Excel sheet with OpenXML). indeed when I save this file with the xlsx format it works fine. please help me to solve this problem.</p>