It means that somewhere a function which should return a image just returned None and therefore has no shape attribute. Try "print img" to check if your image is None or an actual numpy object.

I'm afraid to be obvious but in case you miss: it says 'grad' is None. I would create a breakpoint right after you assign "grad_and_vars" and inspect it

Answering, because the community brought it back. Adding my two objects (cents).

The only reason you see that error is because you are trying to get information or perform operations on an object that doesn't exist in the first place. To check, try printing the object. Like, adding -

print img      # such as this case
print contours # if you are working with contours and cant draw one
print frame    # if you are working with videos and it doesn't show

gives you a None. That means you haven't read it properly. Either the image name you gave does not exist or the path to it is wrong. If you find such an error here's the quick things to do-

1. Check the path or bring your image to the working directory
2. Check the name you gave is right (including the extension- .jpg, .png etc)
3. Put the entire code in a if statement with the object and the code to proceed if true
4. Will add more if suggested in the comments.

The reason behind your error is that the frame is None(Null). Sometimes, the first frame that is captured from the webcam is None mainly because (1) the webcam is not ready yet ( and it takes some extra second for it to get ready) or (2) the operating system does not allow your code to access the webcam.

In the first case, before you do anything on the frame you need to check whether the frame is valid or not :

while True:
 
    frame = image.read()
    if frame is not None:  # add this line
       
      (H, W) = frame.shape[:2]

In the other case, you need to check the camera setting in your Operating system.

Also, for capturing the webcam frames there is another method based on the VideoCapure class in Opencv that might be easier to debug.