Qt 5.15.2 and RaspberryPi4: Problems with OPC-UA Client

  • Dear Community,

    currently I am trying to set up an OPC-UA Client, which I would like to run on a Raspberry Pi 4. I am using a Xubuntu 20.04 Virtual Machine and Qt 5.15.2 for Development tasks. I have some problems with compiling the "connecToEndpoint" function and I cannot find the solution for this problem.

    For the deployment of the modules "qtbase" and "qtopcua" on the Raspberry Pi 4 I used this guide for cross compilation: https://wapel.de/?p=842

    Here is the part of project, which is not working:

    void OpcuaModuleBackend::connectToEndpoint(const QString &url, qint32 index)
        if (m_connected)
        QOpcUaProvider provider;
        if (index < 0 || index >= m_backends.size())
            return; // Invalid index
        if (!m_client || (m_client && m_client->backend() != m_backends.at(index))) {
            if (m_client)
                QObject::connect(m_client.data(), &QOpcUaClient::stateChanged, this, &OpcuaModuleBackend::clientStateHandler);
        if (!m_client) {
            qWarning() << "Could not create client";
            m_successfullyCreated = false;
        m_successfullyCreated = true;

    And the error message after compiling:


    Is there anyone, who had the same problem?
    What can be the solution for this problem?

    Thank you in Advance!

  • Lifetime Qt Champion

    @Mauda The error messages are actually quite clear: there is no connectToEndpoint() method in QOpcUaClient which takes a QUrl parameter. You also can see it if you check documentation: https://doc-snapshots.qt.io/qtopcua/qopcuaclient.html#connectToEndpoint
    You have to pass a parameter of type https://doc-snapshots.qt.io/qtopcua/qopcuaendpointdescription.html

  • Dear jsulm,

    thank you for your reply and your help with description link.
    That helped to solve the problem by my own.

    I replaced



        QOpcUaEndpointDescription d;
        d.setEndpointUrl("ServerAdress"); //Add your server adress

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