<class 'cv2.CascadeClassifier'> returned a result with an error set code example
Example: SystemError: returned a result with an error set
cv2.CascadeClassifier(cv2.data.haarcascades + "haarcascade_frontalface_default.xml")
cv2.CascadeClassifier(cv2.data.haarcascades + "haarcascade_frontalface_default.xml")