C# Web API - 从 excel 文件上传和读取数据而不保存文件

我有一个WebApi，它将接收用户上传的Excel文件作为多部分/表单数据。我需要读取该文件的内容才能更新数据库。我正在考虑使用 EPPlus，但我无法访问该文件。这是代码

public class MyController : APIController
{
    [Route("import")]
    [HttpPost]
    public async Task<HttpResponseMessage> importFile()
    {
        if (!Request.Content.IsMimeMultipartContent())
            return Request.CreateErrorResponse(HttpStatusCode.BadRequest, "ERROR");
        Stream stream = await Request.Content.ReadAsStreamAsync();
        var excel = new ExcelPackage(stream);
        var workbook = excel.Workbook;
        var sheet = excel.Workbook.Worksheets.First();
        ...
}

错误在var sheet = excel.Workbook.Worksheets.First()上，因为工作簿没有任何工作表（但物理文件有 2

）。

我做错了什么？是溪流吗？

我正在尝试为每种类型的 Excel 文件（.xls 或 .xlsx）使用单独的库，但我无法对.xls文件进行此操作。我正在使用ExcelDataReader，代码现在如下所示：

public async Task<HttpResponseMessage> importFile()
    {
        if (!Request.Content.IsMimeMultipartContent())
            return Request.CreateErrorResponse(HttpStatusCode.BadRequest, "NOT MULTIPART");
        Stream stream = await Request.Content.ReadAsStreamAsync();
        //open xlsx file            
        var excel = new ExcelPackage(stream);
        var workbook = excel.Workbook;
        try
        { 
            var sheet = excel.Workbook.Worksheets.First();
            //working fine with EPPlus for .xlsx files 
            return Request.CreateResponse(HttpStatusCode.OK, errors);                
        }catch(Exception)//open xls file
        {  
           //if its a .xls file it will throw an Exception              
        }
        //using ExcelDataReader to open .xls file
        IExcelDataReader excelReader = ExcelReaderFactory.CreateBinaryReader(stream);
        DataSet result = excelReader.AsDataSet();
        // the DataSet is null, stream is setted as ReadOnlyStream and stream.length is throwing an ObjectDisposedException
        return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, "erro");            
    }