我使用的是.net core 6.0。当我从不同位置调用同一方法时，我收到此错误。我尝试从Index内部调用此方法GetEmployeeByEmployeeNumber，但没有收到任何错误，该方法返回的对象employee的值填充为employee

public async Task<IActionResult> Index()
        {
           EmployeeInfo employee =  await _employeeService.GetEmployeeByEmployeeNumber(up.EmployeeId); 
            PopulatePDFDoc();
            return View();
        }


public async Task<EmployeeInfo?> GetEmployeeByEmployeeNumber(string employeeId)
        {
            List<int> emplyoeeInfoId = new List<int>();
            UserPrincipal up = utilities.UserADIdentity.GetADUserInfo(WindowsIdentity.GetCurrent().Name.ToString());

            emplyoeeInfoId = _ackContext.EmployeeInfos.Where(e => e.EmployeeNumber == employeeId).OrderBy(e => e.DateFormFilled).Select(e => e.EmployeeInfoId).ToList();

            var employee = await _ackContext.EmployeeInfos.Include(e => e.EmergencyInfos.Where(p => p.EmployeeInfoId.Equals(emplyoeeInfoId.LastOrDefault()))).Where(e=>e.EmployeeInfoId.Equals(emplyoeeInfoId.LastOrDefault())).FirstOrDefaultAsync();
            return employee;
       }

如果我从PopulatePDFDoc（）内部调用相同的方法GetEmployeeByEmployeeNumber;然后我收到一个错误消息，系统.无效操作异常：'无效操作。连接已关闭。'
下面是我的PopulatePDFDoc

public  async void PopulatePDFDoc()
        {
            AckPackage.Data.PDFPopulate.DocPDF doc = new Data.PDFPopulate.DocPDF();
            EmployeeInfo employee =  await _employeeService.GetEmployeeByEmployeeNumber(up.EmployeeId);
            

        }

下面是错误的屏幕截图：我是新的。net核心。任何帮助这将是高度赞赏。