pypa/pip · error · UnsupportedPythonVersion

Package requires a different Python: not in

Error message

Package {dist.raw_name!r} requires a different Python: {version} not in {requires_python!r}

What it means

_check_metadata_requires_python (resolver.py:105) raises UnsupportedPythonVersion when the running interpreter's version falls outside the package's Requires-Python specifier and --ignore-requires-python is not set. pip checks this to prevent installing a package that declares it cannot run on the current Python.

Solutions

1. Switch to a compatible Python version (pyenv use 3.x / create a matching venv).
2. Pin the package to an older release that supports your Python version.
3. Pass --ignore-requires-python (risky: may install an unusable package).

Example fix

# before
pip install newpkg   # requires Python >=3.10, you run 3.8
# after
pyenv install 3.11 && pyenv shell 3.11 && pip install newpkg

# Before installing, check the package's Requires-Python against your interpreter.
import sys, subprocess, json
ver = f"{sys.version_info.major}.{sys.version_info.minor}.{sys.version_info.micro}"
# e.g. using the JSON API
import urllib.request
for pkg in ["numpy"]:
    data = json.load(urllib.request.urlopen(f"https://pypi.org/pypi/{pkg}/json"))
    rp = data["info"].get("requires_python", "")
    print(f"{pkg} requires_python={rp}; you run {ver}")

When it happens

Trigger: Installing a package whose Requires-Python (e.g. >=3.10) excludes the active interpreter (e.g. 3.8) via the legacy resolver path.

Common situations: Wrong interpreter or venv active; CI pinned to an old Python; a dependency dropped support for your Python version in a new release.

Related errors

• Could not satisfy constraints for
• [dependency-groups] resolution failed for
• Double requirement given
• Invalid requirement
• None metadata found for distribution

AI-assisted analysis of pypa/pip@f399c37189 (2026-08-08). Data as JSON: /api/errors/05855e3a8dc42b61. Report an issue: GitHub.

Appendix: source

Thrown at src/pip/_internal/resolution/legacy/resolver.py:105

        logger.warning(
            "Package %r has an invalid Requires-Python: %s", dist.raw_name, exc
        )
        return

    if is_compatible:
        return

    version = ".".join(map(str, version_info))
    if ignore_requires_python:
        logger.debug(
            "Ignoring failed Requires-Python check for package %r: %s not in %r",
            dist.raw_name,
            version,
            requires_python,
        )
        return

    raise UnsupportedPythonVersion(
        f"Package {dist.raw_name!r} requires a different Python: "
        f"{version} not in {requires_python!r}"
    )


class Resolver(BaseResolver):
    """Resolves which packages need to be installed/uninstalled to perform \
    the requested operation without breaking the requirements of any package.
    """

    _allowed_strategies = {"eager", "only-if-needed", "to-satisfy-only"}

    def __init__(
        self,
        preparer: RequirementPreparer,
        finder: PackageFinder,
        wheel_cache: WheelCache | None,
        make_install_req: InstallRequirementProvider,

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