pip3 install opencv-python fails on 'skbuild'

[Pedroski55]

With some help from askubuntu I got it working:

I used:

sudo apt-get install python3-opencv

I must have installed the module for Python 2!!

I would like to dabble with qr codes.

From here I see I need opencv-python, qrcode and numpy

The FAQ on the link above says:

Q: Pip install fails with ModuleNotFoundError: No module named 'skbuild'?

Since opencv-python version 4.3.0.*, manylinux1 wheels were replaced by manylinux2014 wheels. If your pip is too old, it will try to use the new source distribution introduced in 4.3.0.38 to manually build OpenCV because it does not know how to install manylinux2014 wheels. However, source build will also fail because of too old pip because it does not understand build dependencies in pyproject.toml. To use the new manylinux2014 pre-built wheels (or to build from source), your pip version must be >= 19.3. Please upgrade pip with pip install --upgrade pip.

But, when I try:

pedro@pedro-512ssd:~$ pip3 install --upgrade pip3
Collecting pip3

this fails.

I have:

pedro@pedro-512ssd:~$ pip3 --version
pip 9.0.1 from /usr/lib/python3/dist-packages (python 3.6)

The above FAQ states: "your pip version must be >= 19.3"

I think I should be using pip3, not pip but upgrading pip also fails:

pedro@pedro-512ssd:~$ pip install --upgrade pip
Collecting pip
Cache entry deserialization failed, entry ignored
Could not find a version that satisfies the requirement pip (from versions: )
No matching distribution found for pip
pedro@pedro-512ssd:~$

How can I get cv2 working??