'NoneType' object has no attribute 'shape'

[Deven2705]

Traceback (most recent call last):
File "c:\Users\Downloads\weapon-detection-python-opencv-withyolov5--main\weapon-detection-python-opencv-withyolov5--main\weapon_detection.py", line 18, in
height, width, channels = img.shape
AttributeError: 'NoneType' object has no attribute 'shape'

juat try to solve this problem

and why we have to pip install requirement -r if there is not ,and there is only two module installed.