pypa/pip · error · CommandError

--requirements-from-script can only be given once

Error message

--requirements-from-script can only be given once

What it means

Raised by RequirementCommand.get_requirements() in req_command.py:400 when --requirements-from-script is specified more than once. PEP 723 inline script metadata can only come from a single script file; multiple scripts would create ambiguous dependency resolution, so pip enforces a limit of one.

Source

Thrown at src/pip/_internal/cli/req_command.py:400

                continue
            for parsed_req in parse_requirements(
                filename, finder=finder, options=options, session=session
            ):
                req_to_add = install_req_from_parsed_requirement(
                    parsed_req,
                    isolated=options.isolated_mode,
                    user_supplied=True,
                    config_settings=(
                        parsed_req.options.get("config_settings")
                        if parsed_req.options
                        else None
                    ),
                )
                requirements.append(req_to_add)

        if options.requirements_from_scripts:
            if len(options.requirements_from_scripts) > 1:
                raise CommandError("--requirements-from-script can only be given once")

            script = options.requirements_from_scripts[0]
            try:
                script_metadata = pep723_metadata(script)
            except PEP723Exception as exc:
                raise CommandError(exc.msg)

            script_requires_python = script_metadata.get("requires-python", "")

            if script_requires_python and not options.ignore_requires_python:
                target_python = make_target_python(options)

                if not check_requires_python(
                    requires_python=script_requires_python,
                    version_info=target_python.py_version_info,
                ):
                    raise UnsupportedPythonVersion(
                        f"Script {script!r} requires a different Python: "

View on GitHub (pinned to d7d0d0a394)

Solutions

1. Use only one --requirements-from-script per pip install invocation.
2. Run separate pip install commands for each script.
3. Merge dependencies from multiple scripts into a single requirements file or a single PEP 723 script.

Example fix

# before
pip install --requirements-from-script a.py --requirements-from-script b.py

# after
pip install --requirements-from-script a.py
pip install --requirements-from-script b.py

def validate_single_script(scripts):
    """Ensure only one --requirements-from-script is given."""
    if isinstance(scripts, list) and len(scripts) > 1:
        raise ValueError('--requirements-from-script can only be given once')
    return True

from pip._internal.exceptions import CommandError
try:
    # pip install --requirements-from-script ...
except CommandError as e:
    if '--requirements-from-script' in str(e) and 'once' in str(e):
        # split into separate pip invocations

When it happens

Trigger: Calling `pip install --requirements-from-script a.py --requirements-from-script b.py`. The check at req_command.py:399 verifies len(options.requirements_from_scripts) > 1.

Common situations: Build scripts or Makefiles that accumulate --requirements-from-script flags in a loop. Combining multiple PEP 723 scripts in one pip install call. Misunderstanding that only one script is supported.

Related errors

• Cannot use '--only-dependencies' in combination with {confli
• When restricting platform and interpreter constraints using
• Can not use any platform or abi specific options unless inst
• Platform and interpreter constraints using --python-version,
• --build-constraint cannot be used with --no-build-isolation.

AI-assisted analysis of pypa/pip@d7d0d0a394 (2026-08-04). Data as JSON: /data/errors/5106e7f69f92d1db.json. Report an issue: GitHub.