Defaulting to user installation because normal site-packages is not writeable ERROR: opencv_python-4.1.2+contrib-cp35-cp35m-win_amd64.whl is not a supported wheel on this platform. code example

Example: ERROR: Could not find a version that satisfies the requirement cv2 (from versions: none) ERROR: No matching distribution found for cv2

#Know the reason is really dumb, because the reason is that the package of CV2 is not called cv2 but called opencv-python

pip install opencv-python

#For python3:
pip3 install opencv-python