If you launch Jupyter QtConsole using PySide2 as its Qt bindings, and exit it (even if you immediately close it after doing nothing) you will get this error when closing the window:
$ jupyter-qtconsole Fatal Python error: deallocating None Current thread 0x0000000101896340 (most recent call first): Abort trap: 6
This is probably due to reference counting not being right somewhere - not quite sure where this is happening yet though.
Minimal example:
from PySide2 import QtWidgets app_instance = QtWidgets.QApplication([]) # If this is commented, application doesn't crash on exit anymore. app_instance2 = app_instance w = QtWidgets.QMainWindow() w.setWindowTitle('Hello World!') w.resize(250, 150) w.show() app_instance.exec_()
Stacktrace:
frame #0: 0x00007fffcb80ad42 libsystem_kernel.dylib`__pthread_kill + 10
    frame #1: 0x00007fffcb8f8457 libsystem_pthread.dylib`pthread_kill + 90
    frame #2: 0x00007fffcb770420 libsystem_c.dylib`abort + 129
    frame #3: libpython3.5m.dylib`Py_FatalError(msg="deallocating None") at pylifecycle.c:1385
    frame #4: libpython3.5m.dylib`none_dealloc(ignore=0x000000010165ca38) at object.c:1372
    frame #5: libpython3.5m.dylib`insertdict(mp=0x000000010078dcc8, key=0x0000000106b053e8, hash=-5214649808865345009, value=0x00000001003212f8) at dictobject.c:809
    frame #6: libpython3.5m.dylib`PyDict_SetItem(op=0x000000010078dcc8, key=0x0000000106b053e8, value=0x00000001003212f8) at dictobject.c:1228
    frame #7: libpython3.5m.dylib`_PyModule_ClearDict(d=0x000000010078dcc8) at moduleobject.c:593
    frame #8: libpython3.5m.dylib`_PyModule_Clear(m=0x000000010077df48) at moduleobject.c:544
    frame #9: libpython3.5m.dylib`PyImport_Cleanup at import.c:460
    frame #10: libpython3.5m.dylib`Py_Finalize at pylifecycle.c:576
    frame #11: libpython3.5m.dylib`Py_Main(argc=2, argv=0x0000000100502b70) at main.c:788
    frame #12: python`main(argc=2, argv=0x00007fff5fbff260) at python.c:65
    frame #13: 0x00007fffcb6dc235 libdyld.dylib`start + 1
- is duplicated by
- 
                    PYSIDE-632 Fatal Python error on close when running embedding_in_qt5.py -         
- Closed
 
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