不支持文件类型

我正试图将当前程序所拍摄的图像发送到远程服务器。我的做法是，首先必须将图像保存到用户的工作站，然后我存储该位置并将其传递给我的方法，以便将其传递到我的服务器。

然而，当我运行代码来传递图像时，我会收到一个错误，说我的文件类型不受支持。

下面是我的代码：

public static void HttpUploadFile(string url, string file, string paramName, string contentType, NameValueCollection nvc)
    {
        Console.Write(string.Format("Uploading {0} to {1}", file, url));
        string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
        byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("'r'n--" + boundary + "'r'n");
        HttpWebRequest wr = (HttpWebRequest)WebRequest.Create(url);
        wr.ContentType = "multipart/form-data; boundary=" + boundary;
        wr.Method = "POST";
        wr.KeepAlive = true;
        wr.Credentials = System.Net.CredentialCache.DefaultCredentials;
        Stream rs = wr.GetRequestStream();
        string formdataTemplate = "Content-Disposition: form-data; name='"{0}'"'r'n'r'n{1}";
        foreach (string key in nvc.Keys)
        {
            rs.Write(boundarybytes, 0, boundarybytes.Length);
            string formitem = string.Format(formdataTemplate, key, nvc[key]);
            byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
            rs.Write(formitembytes, 0, formitembytes.Length);
        }
        rs.Write(boundarybytes, 0, boundarybytes.Length);
        string headerTemplate = "Content-Disposition: form-data; name='"{0}'"; filename='"{1}'"'r'nContent-Type: {2}'r'n'r'n";
        string header = string.Format(headerTemplate, paramName, file, contentType);
        byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
        rs.Write(headerbytes, 0, headerbytes.Length);
        FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
        byte[] buffer = new byte[4096];
        int bytesRead = 0;
        while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
        {
            rs.Write(buffer, 0, bytesRead);
        }
        fileStream.Close();
        byte[] trailer = System.Text.Encoding.ASCII.GetBytes("'r'n--" + boundary + "--'r'n");
        rs.Write(trailer, 0, trailer.Length);
        rs.Close();
        WebResponse wresp = null;
        try
        {
            wresp = wr.GetResponse();
            Stream stream2 = wresp.GetResponseStream();
            StreamReader reader2 = new StreamReader(stream2);
            Console.Write(string.Format("File uploaded, server response is: {0}", reader2.ReadToEnd()));
        }
        catch (Exception ex)
        {
            Console.Write("Error uploading file", ex);
            if (wresp != null)
            {
                wresp.Close();
                wresp = null;
            }
        }
        finally
        {
            wr = null;
        }
    }

我这样调用这个方法：

  NameValueCollection nvc = new NameValueCollection();
  nvc.Add("id", "TTR");
  nvc.Add("btn-submit-photo", "Upload");
 HttpUploadFile("http://WebSiteLocation.com/images/uploadimage.html", sfd.ToString(),"image", "image/jpeg", nvc);

在上面的方法中，sfd与我用来保存图像的保存文件对话框有关。错误是：

不支持给定路径的格式。

哪一行突出显示：

 FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);

我认为上面的代码可以发送任何文件，这就是为什么我对这种情况感到困惑。

有人知道原因吗？我花了一段时间研究这个问题，我认为需要一双新的眼睛和大脑。

为了完成，当我调用sfc.ToString()时，我得到的字符串是：

System.Windows.Forms.SaveFileDialog:标题：文件名：C:''Users''MyComputer''Desktop''Img.png

if (file.IndexOfAny(Path.GetInvalidPathChars()) >= 0)
{
    throw new ArgumentException("File name contains invalid characters", "file");
}