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QProcess::start and GDB leading to missing symbols / ?? in stack

  • I am currently having some trouble debugging a program that starts processes via QProcess. Simply executing the binary without dbg works just fine but when I try to debug the executable with gdb I am getting a SIGTRAP when the process has started. After that the stack always shows '??' instead of function names. When continuing I get a SIGILL.

    In my project I also get following output:

    Probes-based dynamic linker interface failed.

    I am not sure whether this is related to loaded plugins or libraries.
    The problem can be reproduced (except from the " Probes-based dynamic linker interface failed." output) with the following code:

    #include <QCoreApplication>
    #include <QProcess>
    #include <QDebug>
    int main(int argc, char *argv[])
        QCoreApplication a(argc, argv);
        QProcess proc;
        QString exe = "echo";
        QStringList arguments;
        arguments << "Test";
        proc.start(exe, arguments);
        if (!proc.waitForFinished()) {
            qDebug() << "failed to start" << proc.exitCode() << proc.errorString();
        qDebug() << "process finished";
        qDebug() << proc.readAllStandardOutput();
        return a.exec();

    My OS is arch linux (up to date)

    • Qt5: qt5-base 5.15.1-1
    • GDB: gdb 9.2-1
    • clang++: clang 10.0.1-1

    Does anybody have an idea what is causing the SIGTRAP when debugging with dbg?

    (This is a copy of my question on stackoverflow:

  • I found out that the trap is not caused when no breakpoint is set.

  • @Uriel-Elias
    I don't know what the cause/solution is, but for Probes-based dynamic linker interface failed you probably need to read and to see where others are reporting it.

  • @JonB thank you for your answer!
    I found these two posts too but I am not sure whether my issue is related to my main problem: Crashing when starting a subprocess.
    Maybe this might explain my problems with "Probes-based dynamic linker interface failed" but I am afraid that the subprocess issue might be a little more tricky...

  • @Uriel-Elias I'm pretty sure I'm hitting a similar issue. Did you find a solution?

  • Yes and no - it seems to have been solved in an update.
    I checked it right now and the issue does not persist.

    I did not really find out what caused the problems.

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