My question is simple, I suppose, but I can't figure out why this is happening.

I have a QTcpServer:

Qt Code: 
  1. //server initialization
  2.     server= new QTcpServer();
  3.     bool success = server->listen(QHostAddress::Any, 10101);
  4.  
  5.     if(!success)
  6.     {
  7.         ui->textEdit->setTextColor(Qt::red);
  8.         ui->textEdit->append(" > Could not create TopMovie Server! \n   Reason: TopMovie Server is already running! \n\n   This Window will automatically close!");
  9.         ui->textEdit->setTextColor(Qt::black);
  10.         QTimer *timer = new QTimer(this);
  11.         connect(timer, SIGNAL(timeout()), this, SLOT(sterge_server()));
  12.         timer->start(3000);
  13.     }
  14.     else
  15.     {
  16.         ui->textEdit->setTextColor(Qt::white);
  17.         ui->textEdit->append(" > TopMovie Server Online!");
  18.         connect(server, SIGNAL(newConnection()), this, SLOT(incomingConnection()));
  19.         ui->textEdit->setTextColor(Qt::black);
  20.         DataBase();
  21.     }
  22.  
  23. //incomingConnection
  24. void TopMovieS::incomingConnection()
  25. {
  26.     int Socketfd=server->nextPendingConnection()->socketDescriptor();
  27.     QTcpSocket *client = new QTcpSocket(this);
  28.     client->setSocketDescriptor(Socketfd);
  29.     clients.insert(client);
  30.  
  31.     string adresa=" > New client from: "+client->peerAddress().toString().toStdString();
  32.     ui->textEdit->setTextColor(Qt::yellow);
  33.     ui->textEdit->append(adresa.c_str());
  34.     ui->textEdit->setTextColor(Qt::black);
  35.  
  36.     connect(client, SIGNAL(readyRead()), this, SLOT(readyRead()));
  37.     connect(client, SIGNAL(disconnected()), this, SLOT(disconnected()));
  38. }
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I read on QTcpServer Documentation that I have to call nextPendingConnection() instead of IncommingConnection(). And also IncommingConnection() needs a QTcpSocket parameter... Anyway, this code on Windows gives a warning every time a new client is connecting: "QSocketNotifier: Multiple socket notifiers for same socket 768 and type Read", but it still works.

On Ubuntu the same code doesn't work. It gives the same error, but doesn't continue: "QSocketNotifier: Invalid socket 24 and type 'Read', disabling..."

Please help me, I am new to Qt and this is my first QTcpServer. I didn't understood everything from documentation, so the code is, I suppose, wrong.

Thank you!