Dan O'Donovan added the comment: Ok, this fail is happening because we're using python3 unicode strings to call the ANSI MessageBoxA function. A possible fix; Encode strings before passing the MessageBoxA (ctypes.txt.diff attached) Alternatively, calls could be made to the unicode MessageBoxW function, but someone who knows about ctypes / Win32 magic numbers would have to look at that. (Inspiration take from this stack overflow question http://stackoverflow.com/questions/18164994/the-ctypes-wraps-messageboxa-exa...) ---------- keywords: +patch Added file: http://bugs.python.org/file35828/ctypes.txt.diff _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue21903> _______________________________________