- python3.6 on ubuntu18.04 is necessary so you CANNOT remove that version(it includes system libraries)
- prerequires: installed python3.8.
- so you've 2 python 3.x(3.6, 3.8)
check current state
$pip -V
(out)pip 20.0.2 from /home/amaruak00/.local/lib/python3.6/site-packages/pip (python 3.6)install venv, dev
$sudo apt-get install python3.8-venv python3.8-devupdate 3.8 pip
$sudo /usr/bin/python3.8 -m pip install --upgrade pip
(upgrading)check
$pip -V
(out)pip 20.0.2 from /home/amaruak00/.local/lib/python3.8/site-packages/pip (python 3.8)setting python3.8 as python3
$sudo update-alternatives --config python3
$sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.8
#check python3.8 as primarly- If some libraries are seems crash, uninstall & reinstall
- (ex)pip uninstall Pillow / pip install Pillow
