pypa/pip · error · SidecarMetadataInconsistent

Requested {ireq} has inconsistent Requires-Python between it

Error message

Requested {ireq} has inconsistent Requires-Python between its PEP 658 .metadata file and the wheel's METADATA: sidecar has {f_val!r}, wheel has {m_val!r}

What it means

Raised as SidecarMetadataInconsistent for Requires-Python when the Python-version constraint in the PEP 658 .metadata sidecar differs from the wheel's METADATA. Checked at prepare.py:323-329; both values stringified. A mismatch could mislead the resolver into accepting or rejecting a wheel for the wrong Python versions.

Source

Thrown at src/pip/_internal/operations/prepare.py:324

            str(wheel_dist.version),
        )

    # For multi-use fields, only report the symmetric difference to avoid
    # unnecessarily flagging matching values.
    sidecar_requires = _canonical_requires(
        req, sidecar_dist, "the PEP 658 .metadata file"
    )
    wheel_requires = _canonical_requires(req, wheel_dist, "the wheel's METADATA")
    if sidecar_requires != wheel_requires:
        raise SidecarMetadataInconsistent(
            req,
            "Requires-Dist",
            ", ".join(sorted(sidecar_requires - wheel_requires)),
            ", ".join(sorted(wheel_requires - sidecar_requires)),
        )

    if sidecar_dist.requires_python != wheel_dist.requires_python:
        raise SidecarMetadataInconsistent(
            req,
            "Requires-Python",
            str(sidecar_dist.requires_python),
            str(wheel_dist.requires_python),
        )

    sidecar_extras = frozenset(sidecar_dist.iter_provided_extras())
    wheel_extras = frozenset(wheel_dist.iter_provided_extras())
    if sidecar_extras != wheel_extras:
        raise SidecarMetadataInconsistent(
            req,
            "Provides-Extra",
            ", ".join(sorted(sidecar_extras - wheel_extras)),
            ", ".join(sorted(wheel_extras - sidecar_extras)),
        )


class RequirementPreparer:

View on GitHub (pinned to d7d0d0a394)

Solutions

1. Purge caches: pip cache purge, clear any mirror/CDN cache, then retry.
2. Reinstall from the official index with the version pinned: pip install --index-url https://pypi.org/simple/ 'pkg==<ver>'.
3. Verify your interpreter satisfies the wheel's actual Requires-Python by inspecting the wheel METADATA directly.
4. Notify the index maintainer to regenerate .metadata on every wheel change.

Example fix

# before: sidecar Requires-Python >=3.8, wheel requires >=3.9 (on Python 3.8)
pip install pkg  # -> SidecarMetadataInconsistent Requires-Python

# after: use a compatible Python or correct index
python3.9 -m pip install --index-url https://pypi.org/simple/ 'pkg==1.0.0'

# compare Requires-Python from sidecar vs wheel
if str(sidecar_requires_python) != str(wheel_requires_python):
    logger.warning("Requires-Python mismatch; trusting wheel METADATA")

def requires_python_match(a, b) -> bool:
    return str(a) == str(b)

When it happens

Trigger: The sidecar's Requires-Python specifier differs from the wheel's METADATA Requires-Python. E.g. sidecar says '>=3.8', wheel says '>=3.9'. Occurs for remote wheels fetched via PEP 658 metadata.

Common situations: Index/mirror serving a stale .metadata from when the package supported a broader Python range. CDN caching issues. Re-uploaded wheel with a tightened Requires-Python but unchanged .metadata.

Related errors

• Requested {ireq} has inconsistent Name between its PEP 658 .
• Requested {ireq} has inconsistent Version between its PEP 65
• Requested {ireq} has inconsistent Provides-Extra between its
• Requested {ireq} has inconsistent Requires-Dist between its
• Requested {ireq} has inconsistent Name: expected {f_val!r},

AI-assisted analysis of pypa/pip@d7d0d0a394 (2026-08-04). Data as JSON: /data/errors/218fc8919057b4dd.json. Report an issue: GitHub.