UDP Class compile error

[jenya7]

I have a UDP Class
udp.h

#include <QObject>
#include <QUdpSocket>

class MyUDP : public QObject
{
    Q_OBJECT

    public:
    explicit MyUDP(QObject *parent = nullptr);
    void Send(QString data, QString remote_ip, quint16 remote_port);
    void Start(QString ip, quint16 port);

    signals:

    public slots:
    void readyRead(QByteArray buffer);

    private:
    QUdpSocket *socket;

};

udp.cpp

#include "udp.h"

MyUDP::MyUDP(QObject *parent) : QObject(parent)
{
    // create a QUDP socket
    socket = new QUdpSocket(this);
}

void MyUDP::Start(QString local_ip, quint16 local_port)
{
    socket->bind(QHostAddress(local_ip), local_port);
    connect(socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
}

void MyUDP::Send(QString data, QString remote_ip, quint16 remote_port)
{
    QByteArray Data;
    Data.append(data);
    socket->writeDatagram(Data, QHostAddress(remote_ip), remote_port);
}

void MyUDP::readyRead(QByteArray buffer)
{
    // when data comes in
    buffer.resize(socket->pendingDatagramSize());

    QHostAddress sender;
    quint16 senderPort;

    socket->readDatagram(buffer.data(), buffer.size(),
                         &sender, &senderPort);

    qDebug() << "Message from: " << sender.toString();
    qDebug() << "Message port: " << senderPort;
    qDebug() << "Message: " << buffer;
}

When I duild I get
debug/udp.o:udp.cpp:(.rdata$.refptr._ZTV5MyUDP[.refptr._ZTV5MyUDP]+0x0): undefined reference to `vtable for MyUDP'
collect2.exe: error: ld returned 1 exit status

What may be a problem?

[VRonin]

Try cleaning your build folder and rerun qmake/cmake

[jenya7]

Did Clean then Rebuild - the same problem.

[CP71]

@jenya7
Hi
Sometimes I have the same issue.
Normally I delete the build folder via the file explorer, but sometimes this operation doesn't fix this problem.
I don't know why, but when I create a new class I sometimes see this issue.
It seems the compiler has a problem with Q_OBJECT macro, indeed the macro seems doesn't be recognized (not change color in the QtCreator editor), when it appears I remove the macro and write again.

[jenya7]

@CP71
Thank you. Deleting the build folder helped.

[CP71]

@jenya7
You are welcome!