Crash-on-exit after call to app.processEvents()

V. Armando Sole sole at
Mon May 25 21:38:05 BST 2020

Hi Ray, 

I do not know if it will help your case. I was getting rid of some
crashes on exit by deleting all widgets that had no parent. For
instance, when closing the QMainWindow by doing: 

    def closeEvent(self, event):
        if __name__ == "__main__":
            app = qt.QApplication.instance()
            allWidgets = app.allWidgets()
            for widget in allWidgets:
                    # we cannot afford to crash here
                    if id(widget) != id(self):
                        if widget.parent() is None:
                    _logger.debug("Error closing widget")
        return qt.QMainWindow.closeEvent(self, event) 

Best regards, 


On 25.05.2020 19:48, Raymond Osborn wrote:

> I added a call to QtWidgets.QApplication.instance().processEvents() in order to force adjustResize() to work when switching tabs (that's another story). It succeeded in fixing my resize issue, but now it triggers a segfault when I exit the application. This seemed to be related to the bug described in One fix, suggested by @ekhumoro on stackoverflow ( was to delete the main window and the app first, but that doesn't seem to fix it. I am running PyQt 5.12 because that is the last version supported by conda, so I can't test the one-exit fix in v5.13, and my users probably wouldn't have it installed anyway. It happens on Macs and linux. 
> What I am asking is if there are additional things to try in addition to @ekhumoro's suggestion? Basically he suggests doing something like: 
> def main():
> app = QApplication(sys.argv)
> main_window = MainWindow()
> app.exec_()
> # ensure correct deletion order
> del main_window, app
> Does anyone understand why the crash only occurs if I have calls to processEvents() in the code? It never happens when I remove them. 
> Thanks, 
> Ray
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