RuntimeError: Virtual environment creation failed, executable /usr/local/bin/python missing

[nschloe]

When running

python3 -m build --sdist --wheel .

on Mac OS, I'm getting

Traceback (most recent call last):
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/runpy.py", line 193, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/__main__.py", line 210, in <module>
    main(sys.argv[1:], 'python -m build')
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/__main__.py", line 202, in main
    build_package(args.srcdir, outdir, distributions, config_settings, not args.no_isolation, args.skip_dependencies)
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/__main__.py", line 81, in build_package
    _build_in_isolated_env(builder, outdir, distributions)
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/__main__.py", line 45, in _build_in_isolated_env
    with IsolatedEnvBuilder() as env:
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/env.py", line 55, in __enter__
    executable, pip_executable = _create_isolated_env(self._path)
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/env.py", line 171, in _create_isolated_env
    executable = _find_executable(path)
  File "/Users/nschloe/Library/Python/3.8/lib/python/site-packages/build/env.py", line 208, in _find_executable
    raise RuntimeError('Virtual environment creation failed, executable {} missing'.format(executable))
RuntimeError: Virtual environment creation failed, executable /usr/local/bin/python missing

Not sure at all whe it would be looking for python in /usr/local. Any idea what's going wrong?

[gaborbernat]

What folder are you running this in?

[nschloe]

A subfolder of $HOME, where the software sits (complete with pyproject.toml etc.).

[layday]

How did you install Python? It looks like sysconfig might've been patched to ignore the value of base.

[nschloe]

Using default Python on MacOS 11.1 here. Hm...

[uranusjr]

default Python on MacOS 11.1

macOS 11.1 does not have a default Python. (Well, technically there is, but it’s not usable in user land, and certainly not located at /usr/local/bin/python.)

[nschloe]

Then I have no idea. It resides in

which python3

/usr/bin/python3

[layday]

I wonder if sysconfig from another Python installation is on your sys.path. Not sure if it'll get us very far, but could you attach the output of these two commands:

python -c "import sysconfig; print(sysconfig.get_paths())"
python -c "import sys; print(sys.path)"

[nschloe]

I played around with it a little more and I'd say this is too hard to figure out remotely. Thanks anyways for your help! I'll post a solution when I found one.

[bryanheinz]

@nschloe were you doing this on an M1 Mac? i ran into this issue last night on an M1 Mac, but ran fine when i tried on an Intel Mac.

[nschloe]

It's an old Intel MacBook Air, but fully upgraded (Big Sur 11.1).

[Patol75]

I am encountering a similar issue on Ubuntu 20.04.3 LTS using Python 3.10, which I installed from the deadsnakes PPA.
python3.10 -m build returns

* Creating venv isolated environment...

Traceback (most recent call last):
  File "/home/thomas/.local/lib/python3.10/site-packages/build/__main__.py", line 372, in main
    built = build_call(
  File "/home/thomas/.local/lib/python3.10/site-packages/build/__main__.py", line 229, in build_package_via_sdist
    sdist = _build(isolation, builder, outdir, 'sdist', config_settings, skip_dependency_check)
  File "/home/thomas/.local/lib/python3.10/site-packages/build/__main__.py", line 140, in _build
    return _build_in_isolated_env(builder, outdir, distribution, config_settings)
  File "/home/thomas/.local/lib/python3.10/site-packages/build/__main__.py", line 104, in _build_in_isolated_env
    with _IsolatedEnvBuilder() as env:
  File "/home/thomas/.local/lib/python3.10/site-packages/build/env.py", line 104, in __enter__
    executable, scripts_dir = _create_isolated_env_venv(self._path)
  File "/home/thomas/.local/lib/python3.10/site-packages/build/env.py", line 258, in _create_isolated_env_venv
    executable, script_dir, purelib = _find_executable_and_scripts(path)
  File "/home/thomas/.local/lib/python3.10/site-packages/build/env.py", line 303, in _find_executable_and_scripts
    raise RuntimeError(f'Virtual environment creation failed, executable {executable} missing')
RuntimeError: Virtual environment creation failed, executable /tmp/build-env-lcuno53i/local/bin/python missing

ERROR Virtual environment creation failed, executable /tmp/build-env-lcuno53i/local/bin/python missing

If, instead, I use Python 3.9, also installed from the deadsnakes PPA, python3.9 -m build completes without errors.

[layday]

It looks like the prefix scheme is changed to posix_local as a result of this patch and build expects that venvs are created using the default (prefix) scheme. However, virtualenv has added support for the venv scheme and the same patch includes:

+_INSTALL_SCHEMES['venv'] = _INSTALL_SCHEMES['posix_prefix']

so venvs are created using a different scheme.

[layday]

We could add another condition here to check for the existence of the venv scheme although I'm -1 on supporting venv before it lands in CPython.