A program written in c ++, qt does not start, tell me what to do?

Question

Qt

When starting the program on Qt, there was such an error, it didn’t happen before, I didn’t make any changes to the program: Starting /home/gravit/build-untitled4-Desktop-Debug/untitled4...
QEventLoop: Cannot be used without QApplication
QDBusConnection: system D-Bus connection created before QCoreApplication. Application may misbehave.
The program has unexpectedly finished.
/home/gravit/build-untitled4-Desktop-Debug/untitled4 crashed The
crash occurs on a line in ui_mainwindow.h centralWidget = new QWidget(MainWindow);
Thanks for the help...

Answer 1

And QApplication has already been created for you at the time of calling this code?