When I run program from Qt Creator icon is visible in tray, but when I run compiled program from "relased" folder I see process of application but no icon in tray
QSystemTrayIcon * tray = new QSystemTrayIcon( QIcon( "ok.png" ), this );
tray->setContextMenu( trayIconMenu );
tray->show();
tray->setVisible( true );
It looks like your image file ok.png was not deployed properly. I would avoid the recommendation of using an absolute path. Please introduce yourself with the Qt-ressource-system: it adds a layer ob indirection to manage ressources like graphics, sound files, .. and Qt will take care of proper deployment: https://doc.qt.io/qt-5/resources.html