What causes "Missing [name] in source." in python-poetry/poetry?

Add a `name` key to each `[[tool.poetry.source]]` entry.

python-poetry/poetry · error · InvalidSourceError

Missing [name] in source.

Error message

Missing [name] in source.

What it means

`InvalidSourceError` from `create_package_source` (factory.py:214-217) when a source entry in `[[tool.poetry.source]]` lacks a `name` key. The name is required to register the repository in the pool; without it Poetry cannot route dependency lookups.

Source

Thrown at src/poetry/factory.py:217

            raise PoetryError(
                "At least one source must not be configured as 'explicit'."
            )

        return pool

    @classmethod
    def create_package_source(
        cls, source: dict[str, str], config: Config, disable_cache: bool = False
    ) -> HTTPRepository:
        from poetry.repositories.exceptions import InvalidSourceError
        from poetry.repositories.legacy_repository import LegacyRepository
        from poetry.repositories.pypi_repository import PyPiRepository
        from poetry.repositories.single_page_repository import SinglePageRepository

        try:
            name = source["name"]
        except KeyError:
            raise InvalidSourceError("Missing [name] in source.")

        pool_size = config.installer_max_workers

        if name.lower() == "pypi":
            if "url" in source:
                raise InvalidSourceError(
                    "The PyPI repository cannot be configured with a custom url."
                )
            return PyPiRepository(
                config=config,
                disable_cache=disable_cache,
                pool_size=pool_size,
            )

        try:
            url = source["url"]
        except KeyError:
            raise InvalidSourceError(f"Missing [url] in source {name!r}.")

View on GitHub (pinned to 92b74dcfe3)

Solutions

Add a `name` key to each `[[tool.poetry.source]]` entry.
Ensure the key is lowercase `name` (TOML keys are case-sensitive).
Validate the table with `poetry check`.

Example fix

# before
[[tool.poetry.source]]
url = "https://my.repo/simple/"
# after
[[tool.poetry.source]]
name = "myrepo"
url = "https://my.repo/simple/"

Defensive patterns

Strategy: validation

Validate before calling

sources = poetry.local_config.get("source", [])
for s in sources:
    if "name" not in s:
        raise SystemExit(f"source missing 'name': {s}")

Type guard

def source_has_name(source: dict) -> bool:
    return isinstance(source, dict) and isinstance(source.get("name"), str) and bool(source["name"].strip())

Prevention

Always include `name = "..."` under `[[tool.poetry.source]]`.
Use lowercase TOML keys (`name`, not `Name`).
Validate pyproject.toml with `poetry check` after edits.

When it happens

Trigger: A source table with only `url = "..."`; a typo like `Name = "..."` (case-sensitive TOML key must be lowercase `name`); a partially commented source block.

Common situations: Hand-editing pyproject.toml; copy-pasting a source block and dropping the name line; mixing `[[tool.poetry.source]]` with a single `[tool.poetry.source]` table.

Related errors

AI-assisted analysis of python-poetry/poetry@92b74dcfe3 (2026-08-04). Data as JSON: /data/errors/aa3e1d969eae6c2e.json. Report an issue: GitHub.