[Qt] Strano problema con download di file

[fermat]

ciao!
al click su un bottone, lancio un metodo per scaricare un file da internet.
la cosa strana è che escono degli errori, però cmq il file viene scaricato.
questi i metodo:

void MainWindow::doDownload()
{
    manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));
    manager->get(QNetworkRequest(QUrl("...............")));
}

void MainWindow::replyFinished(QNetworkReply *reply)
{
    if(reply->error())
    {
        QMessageBox::information(this, tr("HTTP"), tr("Download failed: %1.").arg(reply->errorString()));
    }
    else
    {
        QFile *file = new QFile("C:\\file.xml");
        if(file->open(QFile::Append))
        {
            file->write(reply->readAll());
            file->flush();
            file->close();
        }
        delete file;
        QMessageBox::information(this, tr("HTTP"), tr("Download failed: %1.").arg(reply->errorString()));
        QMessageBox::information(this, "", "Download completato");
    }

    reply->deleteLater();
}

poi, nel logo di qtcreator esc questo:

QSslSocket: cannot resolve TLSv1_1_client_method

QSslSocket: cannot resolve TLSv1_2_client_method
 QSslSocket: cannot resolve TLSv1_1_server_method
 QSslSocket: cannot resolve TLSv1_2_server_method
 QSslSocket: cannot resolve SSL_select_next_proto
 QSslSocket: cannot resolve SSL_CTX_set_next_proto_select_cb
 QSslSocket: cannot resolve SSL_get0_next_proto_negotiated

ed esce anche il MessageBox con l'errore (Unknown erro).
poi esce il MEssageBox con download completato.