继续获取协议“”在Qt中是未知错误

Question

QUrl downloadUrl = QUrl::fromEncoded(downloadUrlStr.toAscii());

qDebug() << downloadUrl.toString();

QNetworkRequest req(downloadUrl);
req.setAttribute(QNetworkRequest::User, id);
QNetworkReply *finalReply = nam->get(req);
connect(finalReply, SIGNAL(finished()),
this, SLOT(dataFetchFinished()));

我在Qt 4.8.4应用程序中有上面的代码，但在dataFetchFinished（）插槽中我一直检测到错误：协议“”未知

调试输出为："http://192.168.1.1/servlet/com.roving.report.view.excel.ExcelReportServlet?file=661&columns=0&srcType=defineBean&width=0&height=0&reportParamsId=100583&cachedId=662&t_i_m_e=1376086878417&pageStyle=0"

非常感谢任何帮助！