python-poetry/poetry · error · PropertyNotFoundError

Key not in config

Error message

Key {'.'.join(keys)} not in config

What it means

Same PropertyNotFoundError raised by FileConfigSource.get_property(), the TOML-file-backed config source. It reads the file (or defaults to {}) then walks the key segments; if any segment is missing it raises this error. Unlike DictConfigSource the data comes from a TOML file on disk, so the root cause is typically a missing or incomplete config file rather than an in-memory state issue.

Solutions

1. Check that the TOML file exists at the expected path (FileConfigSource.file.path) and inspect its contents.
2. Catch PropertyNotFoundError and fall back to the global/merged config value via Config.get() which returns None for missing keys.
3. Use add_property to set the key before reading it if it should always be present.

Example fix

# before
value = source.get_property(["repositories", "myrepo"])
# after
from poetry.config.config_source import PropertyNotFoundError
try:
    value = source.get_property(["repositories", "myrepo"])
except PropertyNotFoundError:
    value = config.get(["repositories", "myrepo"])  # falls through to merged config

from poetry.config.config_source import PropertyNotFoundError

def safe_get_file(source, key, default=None):
    try:
        return source.get_property(key)
    except PropertyNotFoundError:
        return default

def file_key_exists(source, key) -> bool:
    from poetry.config.config_source import PropertyNotFoundError
    try:
        source.get_property(key)
        return True
    except PropertyNotFoundError:
        return False

from poetry.config.config_source import PropertyNotFoundError

try:
    value = file_source.get_property(["repositories", "myrepo"])
except PropertyNotFoundError:
    # Key not present in the TOML config file (or file is missing)
    value = None

When it happens

Trigger: Calling FileConfigSource.get_property(key) when the TOML file either does not exist (defaults to empty dict) or does not contain the requested key path. For instance reading ['repositories','myrepo'] from a poetry.toml that has no [repositories] table.

Common situations: Fresh project with no poetry.toml yet, a corrupted or partially-written config file, a key that was removed via remove_property (which prunes empty parent tables), or querying a key that only exists in the global config but not the local file.

Related errors

• Key not in config
• Invalid TOML file
• A repository with name
• Expected a value for
• Expected one or two arguments (username, password), got

AI-assisted analysis of python-poetry/poetry@92b74dcfe3 (2026-08-04). Data as JSON: /api/errors/3b371a8edb648188. Report an issue: GitHub.

Appendix: source

Thrown at src/poetry/config/file_config_source.py:43

    def __init__(self, file: TOMLFile) -> None:
        self._file = file

    @property
    def name(self) -> str:
        return str(self._file.path)

    @property
    def file(self) -> TOMLFile:
        return self._file

    def get_property(self, key: str | Sequence[str]) -> Any:
        keys = split_key(key)

        config = self.file.read() if self.file.exists() else {}

        for i, sub_key in enumerate(keys):
            if sub_key not in config:
                raise PropertyNotFoundError(f"Key {'.'.join(keys)} not in config")

            if i == len(keys) - 1:
                return config[sub_key]

            config = config[sub_key]

    def add_property(self, key: str | Sequence[str], value: Any) -> None:
        with self.secure() as config:
            keys = split_key(key)

            for i, sub_key in enumerate(keys):
                if sub_key not in config and i < len(keys) - 1:
                    config[sub_key] = table()

                if i == len(keys) - 1:
                    config[sub_key] = value
                    break

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