Unable to download file at URL, works fine in Chromium/Firefox/cURL

[blooglet]

I'm trying to download a private Google Calendar using a QNetworkAccessManager. Google offers an iCal export function through URLs similar to https://www.google.com/calendar/ical/[MY E-MAIL ADDRESS]/private-[RANDOM STRING OF LETTERS AND NUMBERS]/basic.ics. This calendar can be accessed by other applications through this URL, as described in Google Calendar's documentation.

I use the following code to download a file from a given URL.

// _naMgr is a function member of type QNetworkAccessManager
    connect(&_naMgr, SIGNAL(finished(QNetworkReply*)), this, SLOT(buildCalendar(QNetworkReply*)));
    _naMgr.get(QNetworkRequest(_url));

// _naMgr is a function member of type QNetworkAccessManager
    connect(&_naMgr, SIGNAL(finished(QNetworkReply*)), this, SLOT(buildCalendar(QNetworkReply*)));
    _naMgr.get(QNetworkRequest(_url));

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void Calendar::buildCalendar(QNetworkReply* reply) {
    _content = reply->readAll();
 
    // TODO: debug
    QMessageBox msg;
    msg.setText(_content);
    msg.exec();
}

void Calendar::buildCalendar(QNetworkReply* reply) {
    _content = reply->readAll();

    // TODO: debug
    QMessageBox msg;
    msg.setText(_content);
    msg.exec();
}

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So then I tried downloading my private calendar through the URL provided by Google. This works fine in Chromium, vanilla Firefox (i.e. no prior session data or cookies) and cURL. However, when I try to access the URL through my little program I am served with this Dutch error page. (It says "Feed Processing Error".)

Is there something specific in Qt's way of handling URLs that may cause Google's server to respond differently?