C# 上载时自定义HttpContent失败

我有一个跨平台库（.net framework 4.6.2、.net standard 2.0和uwp）。 我已经创建了一个可升级的流内容用于上传

在.net框架和.net标准中，一切都工作得很好，但在UWP中却不是这样。 每次在uwp中，它都会返回

500服务器错误（内部）

当我尝试在没有

ProgressableStreamContent

的情况下上传时，UWP中的一切都很好

这是我的班级：

internal class ProgressableStreamContent : HttpContent
{
    private const int defaultBufferSize = 100 * 1024;

    private HttpContent content;
    private readonly int _bufferSize;
    public UploadProgress UploaderProgress { get; internal set; }

    private readonly Action<UploadProgress> progress;
    public ProgressableStreamContent(HttpContent content, Action<UploadProgress> progress) : this(content, defaultBufferSize, progress) { }
    public ProgressableStreamContent(HttpContent content, int bufferSize, Action<UploadProgress> progress)
    {
        if (bufferSize <= 0)
            throw new ArgumentOutOfRangeException("bufferSize");

        this.content = content ?? throw new ArgumentNullException("content");
        if (bufferSize < 5120)
            bufferSize = defaultBufferSize;
        _bufferSize = bufferSize;
        this.progress = progress;

        foreach (var h in content.Headers)
        {
            Headers.Add(h.Key, h.Value);
        }
    }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
    {
        return Task.Run(async () =>
        {
            var buffer = new byte[_bufferSize];
            TryComputeLength(out var size);
            var uploadedBytes = 0;


            using (var inputStream = await content.ReadAsStreamAsync())
            {
                while (true)
                {
                    var length = await inputStream.ReadAsync(buffer, 0, buffer.Length);
                    if (length <= 0) break;
                    uploadedBytes += length;
                    Invoke(uploadedBytes, size);
                    await stream.WriteAsync(buffer, 0, length);
                    await stream.FlushAsync();
                }
            }
            await stream.FlushAsync();
        });
    }
    void Invoke(long bytes, long size)
    {
        if (UploaderProgress == null)
            UploaderProgress = new UploadProgress();
        UploaderProgress.FileSize = size;
        UploaderProgress.UploadState =  size == bytes ? UploadState.Uploaded : UploadState.Uploading;
        UploaderProgress.UploadedBytes = bytes;
        progress?.Invoke(UploaderProgress);
    }
    protected override bool TryComputeLength(out long length)
    {
        length = content.Headers.ContentLength.GetValueOrDefault();
        return true;
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            content.Dispose();
        }
        base.Dispose(disposing);
    }
}

---

下面的代码应该可以工作。 似乎您使用了不正确的参数

    using (var client = new HttpClient())
    {
        var requestContent = new MultipartFormDataContent("UPLOAD ID");
        byte[] fileBytes = null;// some image
        var imgCnt = new ByteArrayContent(fileBytes);
        imgCnt.Headers.Add("Content-Transfer-Encoding", "binary");
        imgCnt.Headers.Add("Content-Type", "application/octet-stream");

        requestContent.Add(imgCnt, "photo", $"{Path.GetRandomFileName()}.jpg");
        var progressContent = new ProgressableStreamContent(requestContent, 1024, progress);

        var req = await client.PostAsync(new Uri("SOME URI"), progressContent);

    }

    using (var client = new HttpClient())
    {
        var requestContent = new MultipartFormDataContent("UPLOAD ID");
        byte[] fileBytes = null;// some image
        var imgCnt = new ByteArrayContent(fileBytes);
        imgCnt.Headers.Add("Content-Transfer-Encoding", "binary");
        imgCnt.Headers.Add("Content-Type", "application/octet-stream");

        requestContent.Add(imgCnt, "photo", $"{Path.GetRandomFileName()}.jpg");
        var progressContent = new ProgressableStreamContent(requestContent, 1024, progress);

        var req = await client.PostAsync(new Uri("SOME URI"), progressContent);

    }