OpenCV Error: (-215)size.width>0 && size.height>0 in function imshow

Question

I am trying to make a face tracker that combines Haar Cascade Classification with Lucas Kanade good feature detection. However, I keep getting an error that I cannot figure

Answer 1

I have also met this issue. In my case, the image path is wrong, so the img read is NoneType. After I correct the image path, I can show it without any issue.