问将图像保存到GDI+时，MemoryStream中发生了一个泛型错误

EN

images = new List<Bitmap>(seriesDataList.Count());

foreach (var seriesData in seriesDataList)
{
    using (chart = new Chart { Width = ChartWidth, Height = ChartHeight })
    {
        chart.ChartAreas.Add(new ChartArea(seriesData.Key));

        var series = new Series(seriesData.Key)
        {
            ChartType = SeriesChartType.Doughnut,
            Font = ChartTextFont,
            LegendText = "#VALX (#PERCENT)",
        };

        BindSeriesData(seriesData.ToList(), series);
        series["PieLabelStyle"] = seriesData.Count() <= MaxValuesForShowingLabels ? "Outside" : "Disabled";
        series["PieLineColor"] = "Black";
        chart.Series.Add(series);

        var legend = new Legend(seriesData.Key)
        {
            Enabled = true,
            Font = ChartTextFont,
            Docking = Docking.Right,
            Title = seriesData.Key,
            TitleFont = ChartTitleFont,
            TitleAlignment = StringAlignment.Near
        };

        chart.Legends.Add(legend);

        using (var memoryStream = new MemoryStream())
        {
            chart.SaveImage(memoryStream, ChartImageFormat.Jpeg); // Working fine
            images.Add(new Bitmap(memoryStream));
        }
    }
}

using (var fullImage = MergeImages(images))
           {
                using (var memoryStream = new MemoryStream())
                {
                    fullImage.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Jpeg); // ERROR HERE
                    return Convert.ToBase64String(memoryStream.ToArray());
                }
            }