NullReference Error while reading xlsx EPPlus Core - asp.net-core

Question

I'm trying to upload an excel file with EPPlus. I'ts like my excel file was empty, but it has content inside.
Im getting this error:
worksheet.Dimension.Rows = 'worksheet.Dimension.Rows' threw an exception of type 'System.NullReferenceException'
on this line: int rowCount = worksheet.Dimension.Rows;
[HttpPost("Excel")]
public string UploadExcel(IFormFile file)
{
var filePath = Path.GetTempFileName();
FileInfo excel = new FileInfo(filePath);
using (ExcelPackage package = new ExcelPackage(excel))
{
StringBuilder sb = new StringBuilder();
ExcelWorksheet worksheet = package.Workbook.Worksheets[file.FileName];
int rowCount = worksheet.Dimension.Rows;
int ColCount = worksheet.Dimension.Columns;
bool bHeaderRow = true;
for (int row = 1; row <= rowCount; row++)
{
for (int col = 1; col <= ColCount; col++)
{
if (bHeaderRow)
{
sb.Append(worksheet.Cells[row, col].Value.ToString() + "\t");
}
else
{
sb.Append(worksheet.Cells[row, col].Value.ToString() + "\t");
}
}
sb.Append(Environment.NewLine);
}
return sb.ToString();
}

Answer 1

Can you verify that the workshseets are being loaded?
//examine in the debugger to make sure the worksheet you want is loaded
var worksheets = package.Workbook.Worksheets.ToList();
If that doesn't work, can you try one of these?
var worksheet = package.Workbook.Worksheets[0];
var worksheetFirst = package.Workbook.Worksheets.First();
UPDATE:
The real error is that you are trying to read a temp file with var filePath = Path.GetTempFileName();. You need to read an actual excel file. For example, you could use Path.GetFullPath("path/to/the/excel/file.xls");