IndexOutOfRangeException: Worksheet position out of range. using EpPlus

[HttpPost]
public async Task <IActionResult> Import(IFormFile file)
{
if(file ==null||file.Length==0)
return Content("File Not Selected");
string fileExtension=Path.GetExtension(file.FileName);
if(fileExtension==".xls"||fileExtension==".xlsx")
{
var rootFolder=@"Upload";
var fileName=file.FileName;
var filePath=Path.Combine(rootFolder,fileName);
// var filePath = @"Upload/Semester.xlsx";
var fileLocation=new FileInfo(filePath);
using(var fileStream=new FileStream(filePath,FileMode.Create))
{
await file.CopyToAsync(fileStream);
}
if(file.Length<=0)
return BadRequest();
using(ExcelPackage package=new ExcelPackage(fileLocation))
{
ExcelWorksheet workSheet=package.Workbook.Worksheets[0];