python-poetry/poetry · error · ValueError

Invalid layout

Error message

Invalid layout

What it means

Raised by poetry.layouts.layout() at src/poetry/layouts/__init__.py:11-12 when the requested layout name is not a key in _LAYOUTS, which only contains 'src' and 'standard'. ValueError. Used by `poetry new --name=...` and similar scaffolding commands.

Source

Thrown at src/poetry/layouts/__init__.py:12

from __future__ import annotations

from poetry.layouts.layout import Layout
from poetry.layouts.src import SrcLayout


_LAYOUTS = {"src": SrcLayout, "standard": Layout}


def layout(name: str) -> type[Layout]:
    if name not in _LAYOUTS:
        raise ValueError("Invalid layout")

    return _LAYOUTS[name]

View on GitHub (pinned to 92b74dcfe3)

Solutions

1. Use one of the supported names: 'src' or 'standard'.
2. For a src-style project pass `poetry new --src mypkg`.
3. If you need a custom layout, register it by extending the _LAYOUTS dict in your own code path before calling layout().

Example fix

# before
$ poetry new --layout=masonry mypkg
ValueError: Invalid layout

# after
$ poetry new --src mypkg   # uses 'src' layout

SUPPORTED_LAYOUTS = {'src', 'standard'}

def validate_layout(name: str) -> None:
    if name not in SUPPORTED_LAYOUTS:
        raise ValueError(f'Invalid layout {name!r}; choose from {sorted(SUPPORTED_LAYOUTS)}.')

def is_known_layout(name: str) -> bool:
    return name in {'src', 'standard'}

try:
    layout_cls = layout(name)
except ValueError as e:
    if 'Invalid layout' in str(e):
        layout_cls = layout('standard')  # safe fallback for scaffolding
    raise

When it happens

Trigger: Calling layout('masonry') or any name other than 'src'/'standard'. Reached via `poetry new --layout=X myproj` or `poetry new --src` (which selects 'src').

Common situations: Typo in the --layout flag, or assuming a custom layout is registered when it is not. Developers extending Poetry sometimes expect plugin layouts to be auto-registered.

Related errors

• Missing [url] in source {name!r}.
• Setting {self.argument('key')} does not exist
• You can only pass one value.
• "{value}" is an invalid value for {key}
• Group(s) not found: {', '.join(message_parts)}

AI-assisted analysis of python-poetry/poetry@92b74dcfe3 (2026-08-04). Data as JSON: /data/errors/d4297c1add866fb2.json. Report an issue: GitHub.