cv2.COLOR_BGR2GRAY is not working

[nagaajay4]

i don't why for the new version of opencv it is not working..

Traceback (most recent call last):
File "c:/Users/Naja Ajay/Desktop/project/face_detection.py", line 10, in
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.5.1) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-kh7iq4w7\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function
'cv::cvtColor'