Remove deprecated install_ext and ~/.ipython/extensions As pointed out in #13722 loading extensions from this place have been deprecated for about 5 years, so time for removal. I understand this will likely make it too hard for some user who can't seem to be able to write 8 lines of configuration: $ cat mod.py pyproject.toml """ipython ext""" __version__ = "0.0.1" [build-system] requires = ["flit_core >=3.2,<4"] build-backend = "flit_core.buildapi" [project] name = "mod" dynamic = ["version", "description"] Those can be reminded that they can also modify their $PYTHONPATH, so that py files can be imported from their preferred folder. Closes #13722