nodejs/node · error · ExceptionGroup

invalid metadata

Error message

invalid metadata

What it means

An ExceptionGroup (PEP 654) raised by Metadata.from_raw when validation collects one or more InvalidMetadata exceptions during attribute/validator checks. It aggregates every per-field problem rather than failing on the first one, so the developer can see all invalid fields at once.

Source

Thrown at tools/gyp/pylib/packaging/metadata.py:702

                            continue
                        field_age = _VALID_METADATA_VERSIONS.index(
                            field_metadata_version
                        )
                        if field_age > metadata_age:
                            field = _RAW_TO_EMAIL_MAPPING[key]
                            exc = InvalidMetadata(
                                field,
                                "{field} introduced in metadata version "
                                "{field_metadata_version}, not {metadata_version}",
                            )
                            exceptions.append(exc)
                            continue
                    getattr(ins, key)
                except InvalidMetadata as exc:
                    exceptions.append(exc)

            if exceptions:
                raise ExceptionGroup("invalid metadata", exceptions)

        return ins

    @classmethod
    def from_email(
        cls, data: Union[bytes, str], *, validate: bool = True
    ) -> "Metadata":
        """Parse metadata from email headers.

        If *validate* is true, the metadata will be validated. All exceptions
        related to validation will be gathered and raised as an :class:`ExceptionGroup`.
        """
        raw, unparsed = parse_email(data)

        if validate:
            exceptions: list[Exception] = []
            for unparsed_key in unparsed:
                if unparsed_key in _EMAIL_TO_RAW_MAPPING:

View on GitHub (pinned to 1b2de5e052)

Solutions

1. Catch ExceptionGroup and iterate exc.exceptions to see every offending field and its message.
2. Fix each listed field in the METADATA/PKG-INFO source so it conforms to the declared metadata_version.
3. If you intentionally want lenient parsing, pass validate=False to from_raw.

Example fix

# before
meta = Metadata.from_raw(raw, validate=True)

# after
try:
    meta = Metadata.from_raw(raw, validate=True)
except ExceptionGroup as eg:
    for e in eg.exceptions:
        print(e.field, str(e))
    raise

try:
    meta = Metadata.from_raw(raw, validate=True)
except ExceptionGroup as eg:
    fields = [(e.field, str(e)) for e in eg.exceptions if isinstance(e, InvalidMetadata)]
    # report all fields, then decide

When it happens

Trigger: Calling Metadata.from_raw(raw, validate=True) where one or more RawMetadata fields fail their _Validator checks (e.g. a field introduced in a newer metadata version than metadata_version declares, a bad version string, or a malformed value). The loop accumulates InvalidMetadata into 'exceptions' and raises this group when non-empty.

Common situations: Building or inspecting a package whose METADATA file was hand-edited, generated by an older tool, or has a metadata_version that is lower than fields it uses (e.g. using License-Expression without bumping metadata_version to 2.4).

Related errors

• unparsed
• invalid or unparsed metadata
• duplicate labels in project urls
• payload in an invalid encoding
• Invalid specifier: '{spec}'

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/d4f45de57eba7def. Report an issue: GitHub.