I have loaded my app's layout from a hard disk using the functions restoreGeometry and restoreState of QMainWindow. All works fine in Qt 5.x. However, after upgrading to 6.4.x, my app sometimes crashed, caused by restoreState. It still happens even though I removed the old layout data, and saved the new one (fresh data). Removing that function (restoreState) can help the app to run again. Debug can't catch it clearly since it happens with some delay.

The attached image is what I can have sometimes with the debugger