What causes "Env {env_name} doesn't belong to this project." in python-poetry/poetry?

Confirm you are running the command from the correct project directory (where pyproject.toml lives).

python-poetry/poetry · error · IncorrectEnvError

Env {env_name} doesn't belong to this project.

Error message

Env {env_name} doesn't belong to this project.

What it means

Raised as IncorrectEnvError in EnvManager.remove when the user passes a full path to a python executable and the env directory that interpreter reports does not begin with the current project's base_env_name. Poetry derives project ownership from the env name prefix and refuses to operate on another project's virtualenv.

Source

Thrown at src/poetry/utils/env/env_manager.py:291

        Check if env name starts with projects name.

        This is done to prevent action on other project's envs.
        """
        return env.startswith(base_env_name)

    def remove(self, python: str) -> Env:
        python_path = Path(python)
        if python_path.is_file():
            # Validate env name if provided env is a full path to python
            try:
                env_dir = subprocess.check_output(
                    [python, "-c", GET_ENV_PATH_ONELINER], text=True, encoding="locale"
                ).strip("\n")
                env_name = Path(env_dir).name
                if not self.check_env_is_for_current_project(
                    env_name, self.base_env_name
                ):
                    raise IncorrectEnvError(env_name)
            except CalledProcessError as e:
                raise EnvCommandError(e)

        if self.check_env_is_for_current_project(python, self.base_env_name):
            venvs = self.list()
            for venv in venvs:
                if venv.path.name == python:
                    # Exact virtualenv name
                    if self.envs_file.exists():
                        venv_minor = ".".join(str(v) for v in venv.version_info[:2])
                        self.envs_file.remove_section(self.base_env_name, venv_minor)

                    self.remove_venv(venv.path)

                    return venv

            raise ValueError(
                f'<warning>Environment "{python}" does not exist.</warning>'

View on GitHub (pinned to 92b74dcfe3)

Solutions

Confirm you are running the command from the correct project directory (where pyproject.toml lives).
If the project moved, the env name prefix changed - recreate with 'poetry env remove' by its listed name or 'poetry env list' then remove by version.
Remove the foreign env manually with its owning project rather than from here.
Run 'poetry env list' to see which envs belong to this project and remove one of those.

Example fix

// before - path points into another project's venv
manager.remove("/home/u/other-project/.venv/bin/python")  # IncorrectEnvError

// after - remove by the env name listed for THIS project
manager.remove("myproject-py3.11")

Defensive patterns

Strategy: validation

Validate before calling

from pathlib import Path

def env_belongs_to_project(manager, python_path: str) -> bool:
    p = Path(python_path)
    if not p.is_file():
        return False
    import subprocess
    try:
        env_dir = subprocess.check_output(
            [python_path, "-c", "import sys; print(sys.prefix)"], text=True
        ).strip()
    except subprocess.CalledProcessError:
        return False
    return Path(env_dir).name.startswith(manager.base_env_name)

Type guard

from poetry.utils.env.exceptions import IncorrectEnvError, EnvError

def is_incorrect_env(e: Exception) -> bool:
    return isinstance(e, IncorrectEnvError) or (isinstance(e, EnvError) and "belong to this project" in str(e))

Try / catch

from poetry.utils.env.exceptions import IncorrectEnvError

try:
    manager.remove(python_path)
except IncorrectEnvError as e:
    raise SystemExit(f"Refusing to remove env not owned by this project: {e}")

Prevention

Always run env commands from the project root containing pyproject.toml.
Prefer removing envs by their listed name ('poetry env list') rather than by raw interpreter path.
Remember base_env_name is derived from cwd - moving the project directory invalidates old env names.
Never point env remove at a global or foreign project interpreter.

When it happens

Trigger: Calling 'poetry env remove /path/to/some/python' where that python lives in a venv belonging to a different project (env_dir.name does not start with this project's base_env_name, checked at env_manager.py:288-291).

Common situations: Pointing env remove at a globally-installed python, a venv from another project, or a shared interpreter; running the command from the wrong project directory; project path changed so base_env_name (which is hashed from cwd) no longer matches the previously-created env.

Related errors

AI-assisted analysis of python-poetry/poetry@92b74dcfe3 (2026-08-04). Data as JSON: /data/errors/cc7530e4865aefec.json. Report an issue: GitHub.