python-poetry/poetry · error · PoetryError

Failed to install {path}

Error message

Failed to install {path}

What it means

pip_install wraps environment.run_pip(*args) in try/except EnvCommandError and re-raises as PoetryError('Failed to install {path}') chaining the original EnvCommandError as __cause__. It means the underlying `pip install` invocation exited non-zero for the given path.

Source

Thrown at src/poetry/utils/pip.py:58

    if upgrade:
        args.append("--upgrade")

    if not deps:
        args.append("--no-deps")

    if editable:
        if not path.is_dir():
            raise PoetryError(
                "Cannot install non directory dependencies in editable mode"
            )
        args.append("-e")

    args.append(str(path))

    try:
        return environment.run_pip(*args)
    except EnvCommandError as e:
        raise PoetryError(f"Failed to install {path}") from e

View on GitHub (pinned to 92b74dcfe3)

Solutions

1. Inspect the chained EnvCommandError (the __cause__) for pip's actual stderr/stdout to find the real reason.
2. Confirm the path exists and is a valid package/wheel for the target interpreter.
3. Check write permissions on environment.path and available disk.
4. If deps=True, resolve the underlying dependency conflicts or install with --no-deps where appropriate.

Example fix

# before
try:
    pip_install(path, env)
except PoetryError:
    pass   # original pip stderr is lost
# after - surface the real cause
try:
    pip_install(path, env)
except PoetryError as e:
    raise RuntimeError(f'pip failed: {e.__cause__}') from e

from pathlib import Path

def installable(path: Path, env) -> bool:
    return path.exists() and env.path.exists() and os.access(env.path, os.W_OK)

from poetry.exceptions import PoetryError
try:
    pip_install(path, environment)
except PoetryError as e:
    cause = e.__cause__   # the underlying EnvCommandError with pip's stderr
    print('pip stderr:', getattr(cause, 'output', cause))
    raise

When it happens

Trigger: Any pip_install where pip fails: dependency conflict, incompatible/unsupported wheel for the interpreter, permission denied on the env prefix, network failure fetching deps (when deps=True), or a corrupt package.

Common situations: Installing a wheel built for a different Python/ABI/platform; permission errors writing into the environment prefix; pip resolver conflict when deps are not suppressed; transient network errors.

Related errors

• Cannot install non directory dependencies in editable mode
• Could not find a matching version of package {name}
• Invalid package definition.
• The following packages were not found: {', '.join(sorted(not
• Failed to install required Poetry plugins

AI-assisted analysis of python-poetry/poetry@92b74dcfe3 (2026-08-04). Data as JSON: /data/errors/a5da19538ebf4e4b.json. Report an issue: GitHub.