Would you mind sharing your workflow yml file and an example repo to reproduce this issue ? 

@yanjingzhu sure, here is an example:

run-package-macos:
   name: test
   runs-on: macOS-latest
steps:

- name: Checkout

uses: actions/checkout@master

- name: Set up Python 2.7

uses: actions/setup-python@v1

with:

python-version: 2.7

- name: install custom lib

run: |

cd lib

pip install -r requirements.txt

python setup.py install

...

- name: build

run: |

...

python setup.py clean build

...

When I run the generated build, I got the zlib error. Same issue with python 3…8.  Using this following wa it works well:

- name: install python with zlib wa
  run: |
        brew update
        brew install zlib
        export CFLAGS="-I$(brew --prefix openssl)/include -I$(xcrun --show-sdk-path)/usr/include"
        export LDFLAGS="-L$(brew --prefix openssl)/lib"
        brew install pyenv
        pyenv install 2.7
        pyenv global 2.7

Thxs a lot! :slight_smile: