Excel Package throws System.IO.FileFormatException: File contains corrupted data

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C#

I am trying to upload an Excel file with .xls and .xlsx formats and save it into a local C: Drive and then convert it into Datatable.

I am getting File Format Exception near

using (ExcelPackage xlPackage = new ExcelPackage(existingFile))

Code:

DataTable dt;
string XmlString = string.Empty;     

string strFile = ExcelFileUpload.FileName;
var fileExt = System.IO.Path.GetExtension(ExcelFileUpload.FileName);
if (fileExt == ".xlsx" || fileExt == ".xls")
{
    ExcelFileUpload.SaveAs("C:\\Docs\\" + strFile);
    FileInfo existingFile = new FileInfo("C:\\Docs\\" + strFile);
    using (ExcelPackage xlPackage = new ExcelPackage(existingFile)) ***//throws Exception***
    {
        ExcelWorksheet worksheet = xlPackage.Workbook.Worksheets[1];
        dt = new DataTable(); 
    }
}