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QProcess : "Process failed to start : No such file or directory"

  • Hello everyone,

    I develop an application with Qt Creator 4.3.1 (based on Qt 5.9.1) (MVC 2015, 32 bit). I'm on windows 10 x64 and my application is in C++.

    This is part of my main function :

    void fenetreprincipale::on_boutton_ValiderParametres_clicked(){
            argumentsROI = ajoutDesArguments();
            else if(ui->check_seuil->isChecked()){
                    /*To DO*/

    now this is a function i use :

    QStringList fenetreprincipale::ajoutDesArguments(){
        return arguments;
    bool fenetreprincipale::lancementDuProgrammeROI(){
        processusOK = true;
            processusOK = false;
            QMessageBox::warning(this, "Erreur", "Le processus roi n'a pas démarré.\n"+processusROI.errorString());
                processusOK = false;
                QMessageBox::warning(this, "Erreur", "Le processus roi ne c'est pas terminé.\n"+processusROI.errorString());
        return processusOK;

    here is my class fenetrePrincipale.h :

    #include <QMainWindow>
    #include <QFileDialog>
    #include <QMessageBox>
    #include <QDir>
    #include <QProcess>
    namespace Ui {
        class fenetreprincipale;
    class fenetreprincipale : public QMainWindow{
        explicit fenetreprincipale(QWidget *parent = 0);
    private slots:
        void on_boutton_ParcourirFichier_clicked();
        void on_boutton_ValiderParametres_clicked();
        Ui::fenetreprincipale *ui;
        QStringList argumentsROI;
        QStringList ajoutDesArguments();
        bool lancementDuProgrammeROI();
        QString nomDuFichier_clone;
        QString nomDuDossierDesResultats;
        QDir dossierDesResultats;
        QString nomDuJeuDeDonne;
        QString variance;
        QString seuil;
        QString gain;
        QStringList arguments;
        bool processusOK;
        QProcess processusROI;
        QString nomDuProgrammeROI = "roi.exe";

    I don't understand my error.
    Furthermore there are tree week it works.
    the only element changed is a deleted directory (with program roi.exe i use).
    I download it again on github. But i'm sure i add *.dll on it and i don't remember there name.

    Please help me.

  • Lifetime Qt Champion


    Where is roi.exe located on your system ?

  • @SGaist hi,

    roi.exe is in the directory of my program.

    Thanks for reply :)

    mon dossier

  • Lifetime Qt Champion

    Then I'd use the full path to it in your application rather than relying on that. The working directory may not be the same as the one your program is stored in.

    You can use QApplication::applicationDirPath for that.

  • @SGaist Thank you It seems to be that !
    I continue and i tell you if it's always ok.

  • I add my next verification :

         if(processusROI.exitCode() == 0){
              /*TO DO*/
          else if(processusROI.error() != 0){
               QMessageBox::warning(this, "Erreur", "Le programme roi a planté.\n"+statutDeLApplication.number(processusROI.exitStatus())+" : "+processusROI.errorString());

    I obtain this :

  • Lifetime Qt Champion

    What kind of application is roi.exe ?

  • @SGaist

    it's an application in C use library gsl, hdf5, (fits at the end).
    I compile it (and it works with cygwin)

    If you realy want to see the project i use is here :

    the compilation line on cygwin an terminal linux :

    gcc -W -g -o code/roi code/roi.c -lgsl -lgslcblas -lhdf5 -lhdf5_hl -lm -std=gnu11

    and the execution is :

    ./code/roi -f Data_POMC.hdf5 -d stack -g 0.14 -v 290 -m > out/rss_stat 

    I think it's a problem of dll missing in this directory but i don't find them.

  • Lifetime Qt Champion

    You can use Dependency Walker to check what roi.exe needs to run

  • @SGaist I have already used it but after download 45 *.dll "API...." (and i don't find all in I'm desesperate.

    I see they are some *dll in 32bits and other in 64bits it's that ?
    How i resolved it ?

    Thanks again for your time :)

    dependency walker

  • new view :
    dependency walker

  • Lifetime Qt Champion

    The only files of real interest are the CYG**.dll the others are systems dll that you shouldn't need to do anything special for.

  • @SGaist ok, thanks!
    And use this dll in c:cygwin64.
    Why is'nt good ?
    (I put new pictur in my last post)

    I try to make same reserche with my c++ project and i see this (it's only a part of result):

    dependency Walker

    my project is in x86.
    Do i change all my dll in x86 ?

  • thanks @SGaist I resolved my problem <3

    In case of i loos it again or an other developper whant it i add :

    • cygblas-0.dll
    • cyggcc_s-1.dll
    • cyggcc_s-seh-1.dll
    • cyggfortran-3.dll
    • cyggsl-19.dll
    • cyghdf5_hl-10.dll
    • cyghdf5-10.dll
    • cygquadmath-0.dll
    • cygwin1.dll
    • cygz.dll

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