pypa/pip · error · InstallationError

Error reading

Error message

Error reading {path}: {e}

What it means

An OS-level error other than FileNotFoundError or TOMLDecodeError occurred while reading pyproject.toml for dependency-group resolution. This is typically a permission denied, or a disk/IO error. The generic OSError is caught and wrapped.

Solutions

1. Check file permissions: 'ls -l pyproject.toml' and ensure you have read access
2. Fix ownership or permissions: 'chmod +r pyproject.toml' or 'chown $USER pyproject.toml'
3. If on a network filesystem, verify connectivity and retry
4. On Windows, check the file is not locked by another process

import os

def is_readable(path: str) -> bool:
    return os.path.isfile(path) and os.access(path, os.R_OK)

if not is_readable("pyproject.toml"):
    print("pyproject.toml is not readable — check permissions")

import os

def is_readable_file(path: str) -> bool:
    """Type guard: True if path is a readable file."""
    return os.path.isfile(path) and os.access(path, os.R_OK)

from pip._internal.exceptions import InstallationError
from pip._internal.req.req_dependency_group import parse_dependency_groups

try:
    reqs = parse_dependency_groups([("pyproject.toml", "dev")])
except InstallationError as e:
    if "Error reading" in str(e):
        print("Check file permissions: chmod +r pyproject.toml")
    else:
        raise

When it happens

Trigger: pyproject.toml exists but cannot be opened due to restrictive file permissions, or the filesystem is experiencing I/O errors. A race condition where the file is deleted between the existence check and the open call.

Common situations: File owned by root or another user with no read permission. Docker volume mount issues. Network filesystem (NFS) hiccups. File locked by another process on Windows.

Related errors

• [dependency-groups] resolution failed for
• [dependency-groups] table was missing from
• Error parsing
• not found. Cannot resolve '--group' option.
• An error occurred while writing to the configuration file

AI-assisted analysis of pypa/pip@f399c37189 (2026-08-08). Data as JSON: /api/errors/0fbb9f463fd72aeb. Report an issue: GitHub.

Appendix: source

Thrown at src/pip/_internal/req/req_dependency_group.py:86

    return resolvers


def _load_pyproject(path: str) -> dict[str, Any]:
    """
    This helper loads a pyproject.toml as TOML.

    It raises an InstallationError if the operation fails.
    """
    try:
        with open(path, "rb") as fp:
            return tomllib.load(fp)
    except FileNotFoundError:
        raise InstallationError(f"{path} not found. Cannot resolve '--group' option.")
    except tomllib.TOMLDecodeError as e:
        raise InstallationError(f"Error parsing {path}: {e}") from e
    except OSError as e:
        raise InstallationError(f"Error reading {path}: {e}") from e

View on GitHub (pinned to f399c37189)