TempFileName = Regex.Replace(vehicle.FileUpload.FileName, "[^a-zA-Z0-9_]+", "_", RegexOptions.Compiled);
var directiveToUpload = Path.Combine(_hostingEnvironment.WebRootPath, "images\UploadFile");

    if (!System.IO.Directory.Exists(directiveToUpload))
                        {
                            System.IO.Directory.CreateDirectory(directiveToUpload);
                        }
    await SaveFileToServer(TempFileName);

async Task SaveFileToServer(string FileName)
            {

                if (vehicle.FileUpload.Length > 0)
                {
                    using (var stream = new FileStream(Path.Combine(directiveToUpload, FileName), FileMode.Create))
                    {
                        await vehicle.FileUpload.CopyToAsync(stream);
                    }
                }
            }