Problems using zsh with Catalina, Python/Python3, pip/pip3, PATH, zshrc, etc

I had a similar problem. You can use

rehash

in your command line to update your paths. It solved the issue for me.

I've experienced this issue after a clean installation of Catalina. I'm also using zsh.

What I did wrong:

I've installed a new version of pip by using:

sudo pip3 install --upgrade pip

as prompted. However, this will not work with Apple's python, as the path will not be correct. Instead, sudo -H should be used.

How I fixed pip:

Fortunately, python3 -m pip still works as a workaround for pip3.

Install an older version of pip (in my case, 19.3.0 was sufficient):

sudo -H python3 -m pip install --upgrade pip==19.3.0

and then upgrade again:

sudo -H python3 -m pip install --upgrade pip

I hope this will also solve your issue.

I had the same issue as you. Solved with

brew install python3