Installing lxml for Python on an M1/M2 Mac

I ran into this error while trying to run pip install lxml on an M2 Mac, inside a virtual environment I had intitially created using pipenv shell:

% pip install lxml
Collecting lxml
  Using cached lxml-4.9.2.tar.gz (3.7 MB)
  Preparing metadata ( ... done
Building wheels for collected packages: lxml
  Building wheel for lxml ( ... error
  error: subprocess-exited-with-error
  × python bdist_wheel did not run successfully.
  │ exit code: 1
  ╰─> [121 lines of output]
      src/lxml/etree.c:96:10: fatal error: 'Python.h' file not found
      #include "Python.h"
      1 error generated.
      Compile failed: command '/usr/bin/clang' failed with exit code 1

I eventually realized that this was using the system Python - /usr/bin/python3 - which doesn't have access to the necessary headers needed to build lxml.

I had also installed Python using Homebrew, which DOES include those headers - but the environment I was working in was using a different Python version.

I'm using pipenv to manage my environments, so the fix for me was to do this:

pipenv --python /opt/homebrew/bin/python3.11

(/opt/homebrew/bin/python3.10 would have worked too.)

Then within my new environment pip install lxml worked just fine.

If I wasn't using pipenv I would run this command to create a fresh virtual environment instead:

/opt/homebrew/bin/python3.11 -m venv venv
venv/bin/pip install lxml

Created 2023-01-27T22:58:58-08:00, updated 2023-01-28T02:35:44-08:00 · History · Edit