No reply data with QNetworkAccessManager when running on another machine

Question

I have a simple program that should retrieve the HTML from a website URL.

main.cpp

#include "Downloader.h"
#include <QCoreApplication>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    auto dl = new Downloader(&a);
    QString url = "https://www.dognow.at/ergebnisse/?page=1";
    dl->fetch(url);
    return a.exec();
}

Downloader.h

#ifndef DOWNLOADER_H
#define DOWNLOADER_H

#include <QNetworkReply>
#include <QObject>

class Downloader : public QObject
{
    Q_OBJECT
    public:
        explicit Downloader(QObject* parent = nullptr);
        void fetch(QString &url);

    private:
        QNetworkAccessManager* m_manager;
    private slots:
        void replyFinished(QNetworkReply* rep);
};
#endif // DOWNLOADER_H

Downloader.cpp

#include "Downloader.h"
#include <QDebug>

Downloader::Downloader(QObject* parent): QObject(parent),
    m_manager(new QNetworkAccessManager(parent))
{}

void Downloader::fetch(QString& url)
{
    qDebug() << "fetch " << url;
    connect(m_manager, &QNetworkAccessManager::finished, this,  &Downloader::replyFinished);
    m_manager->get(QNetworkRequest(QUrl(url)));
}

void Downloader::replyFinished(QNetworkReply* rep)
{
     QByteArray data=rep->readAll();
     QString str(data);
     qDebug() << "data len: " << str.length();
     rep->close();
}

When I run the program on my local PC it works fine. When I run it on another machine the reply data is empty. On both systems I use Linux (x86_64) and Qt 5.15.0.

I hope someone can give me a hint where I should have a look at.

UPDATE: 2022-04-04 - 16:22: when I run a simple curl command on the failing machine it works fine.

Answer 1

Ok, I found the problem. On the failing machin I have an older ubuntu (16.04 LTS) running with an incompatible openssl version. I found it out because I copied my own Qt libs build (debug) to the other machine and I got SSL error (incompatbile version). I installed a newer openssl version and know it works.