在写入所有字节之前无法关闭流

我正在向 API 服务器发送 POST 请求，并且我已经重用了之前在其他服务器上成功完成此操作的代码，并且由于某种原因（我无法弄清楚为什么）它不起作用。我收到错误：

“在写入所有字节之前无法关闭流。”

即使我正确声明了内容长度，但我不确定我在这里缺少什么......

            data = data + "</posts>"
            Dim postBytes As [Byte]() = Encoding.UTF8.GetBytes(data)
            Thread.Sleep(10000)
            track = data
            If uri.Scheme = uri.UriSchemeHttps Then
                Dim request As HttpWebRequest = HttpWebRequest.Create(url)
                request.Method = "POST"

' //通常我只使用 request.contentlength = postbytes.length 或 data.length

                request.ContentLength = System.Text.Encoding.UTF8.GetByteCount(data)
                request.ContentType = "application/xml"
                request.KeepAlive = False
                request.Timeout = 120000
           request.Credentials = New  System.Net.NetworkCredential("xxxxxxxxxxxx",  "xxxxxxxxx")

                Using writer As New StreamWriter(request.GetRequestStream(), Encoding.UTF8)
                    writer.Write(postBytes)
                    writer.Flush()
                    writer.Close()
                End Using
                Using oResponse As HttpWebResponse = request.GetResponse()
                    Dim reader As New StreamReader(oResponse.GetResponseStream())
                    responseData = reader.ReadToEnd()
                    reader.Close()
                    oResponse.Close()
                End Using
                request.Abort()

            End If

        End If
    Catch e As WebException

....

The Exception被抛出是因为您写入的字节数少于WebRequest期望。例如，如果您在中设置了 75 个字节ContentLength属性，并且您在上写入 69 个字节RequestStream并关闭它，将抛出异常。