cv2.error: OpenCV(4.7.0) D:\a\opencv-python\opencv-python\opencv\modules\objdetect\src\cascadedetect.cpp:1689: error: (-215:Assertion failed) !empty() in function 'cv::CascadeClassifier::detectMultiScale'
（1）路径写错了，多了斜杠
（2）img = cv2.imread(“…/data/lena.jpg”)
路径中不能有中文路径不对也会报错