I just bumped into this issue on Ubuntu 24.04. Was trying to package something with hatchling but there was no way. However, in this release the solution proposed by Thomas Ward does not apply, as the ad hoc use of package managers is not longer allowed:
$ sudo pip3 install twine
error: externally-managed-environment
× This environment is externally managed
╰─> To install Python packages system-wide, try apt install
python3-xyz, where xyz is the package you are trying to
install.
If you wish to install a non-Debian-packaged Python package,
create a virtual environment using python3 -m venv path/to/venv.
Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
sure you have python3-full installed.
If you wish to install a non-Debian packaged Python application,
it may be easiest to use pipx install xyz, which will manage a
virtual environment for you. Make sure you have pipx installed.
See /usr/share/doc/python3.12/README.venv for more information.
note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
Therefore building and packaging must be executed from a virtual environment:
sudo apt purge twine
python3 -m venv env-build
source env-build/bin/activate
pip3 install build twine