ImportError: No module named 'Cython'

just directly install from pypi: pip install Cython
https://pypi.org/project/Cython/

Use Pip3 command:

pip3 install --upgrade cython

The problem for me was the pip version. Running python -m pip install pip --upgrade solved the issue.

it should be path problem. go to windows search for python idle right click idle - open file location where right click on python.exe - open file location if the module not in that location type cmd and press enter in path now install module with pip install cython it will work fine

I personally ran into this problem when I was trying to set up a new virtual environment. I simply installed Cython with python -m pip install Cython and then proceeded to install all the rest of my stuff I needed with python -m pip install -r requirements.txt. Once it was done, it actually uninstalled Cython for me... Why? Heck do I know... I ain't that kind of expert :<