zsh returns bad interpreter after Catalina upgrade

After couple of different solutions I tried I managed to make it work with RVM.

Install rvm from terminal:

\curl -sSL https://get.rvm.io | bash -s stable

Once installation is complete, it will say something like:

To start using RVM you need to run `source /Users/{username}/.rvm/scripts/rvm`

So copy/paste that into terminal, and then install ruby version you want, I used:

rvm install 2.6.5

Now when you have your ruby in place you should be able to install gems for the version you've chosen, eg I installed bundler

gem install bundler

This will make rvm as default ruby manager, and will use 2.6.5 from terminal. Hope that helps.

For me the version of the ruby installed with Catalina was newer. I only had to reinstall the missing gems so if you already have ruby installed, this might fix it:

gem install colorls

Here's what helped me:

brew install cocoapods --build-from-source

then:

brew link --overwrite cocoapods