title: C# opening Excel: Exception from HRESULT: 0x800A03EC
body: <p>In my app I need to open an existing Excel file to write/rewrite some data in rows. </p>
  
  <p>Using VS Express 2015, making a Windows Form App.</p>
  
  <p>When I run the app and click on the button that should open, write and close Excel, I got this: </p>
  
  <blockquote>
    <p>An unhandled exception of type
    'System.Runtime.InteropServices.COMException' occurred in
    WindowsFormsApplication2.exe Additional information: Exception from
    HRESULT: 0x800A03EC</p>
  </blockquote>
  
  <p>It points to the line in the code which should open the Excel file.</p>
  
  <pre><code> // Open EXCEL
         Excel.Application EXCEL = new Excel.Application();
         string path = "D:\\profily.xls";
          Excel.Workbook Wbook = EXCEL.Workbooks.Open(path , 0, false, 2, "", "", false, Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false); // THERE IS PROBLEM
        Excel.Worksheet Sheet;
  </code></pre>