A bug? QBasicTimer::start: QBasicTimer can only be used with threads started with QThread

QtTester

Hi,all:
I have encountered an interesting problem.

Qt5.14.1 + VS2017 32bit + Win 10

I have a exe project and an MainWindow project. exe to show MainWindow.

Scene 1: exe + QPluginLoader(MainWindow), call MainWindow as a qt plugin, when i close ,it says:

QBasicTimer::start: QBasicTimer can only be used with threads started with QThread

especially when you drag a QComboBox to the ui.
without QComboBox, it says nothing.

Scene 2:exe + QLibrary("Mainwindow.dll"), call MainWindow as a dynamic library, when i colse ,it says nothing. every goes OK.
even I added QComboBox to the Ui.

I donot use any qthread, or qtimer. only a new mainwindow skeleton project from widzard.
Anyone has this problem ,and how does it happen?
thanks.

Kent-Dorfman

that doesn't seem right. You should be able to instantiate a Qtimer or similar in any class derived from QObject.

QtTester

@Kent-Dorfman
I do think it's a qt bug. When i load other UI with QtPlugLoader just inherited from QWidget, the warning will not appear.

JKSH

@QtTester Before you quit your application:

Make sure that your MainWindow is closed and deleted
Call QPluginLoader::unload()

Does the warning message still appear?

Daniel X

Just chiming in for search engine posterity, in case this helps anyone: I was getting this error because I was inadvertently delete-ing a QComboBox after my QApplication instance had already been destroyed.