pathwaycom/pathway · error · ImportError

{e}. Consider installing 'pathway[{extra}]'

Error message

{e}. Consider installing 'pathway[{extra}]'

What it means

pathway.optional_imports.optional_imports is a contextmanager wrapping imports of optional dependencies. When an ImportError escapes the wrapped block, it is re-raised with a suffix telling you which Pathway optional-extra provides the missing module, e.g. "No module named 'weaviate'. Consider installing 'pathway[weaviate]'". It exists so missing optional dependencies surface an actionable message instead of a bare ModuleNotFoundError.

Source

Thrown at python/pathway/optional_import.py:11

# Copyright © 2026 Pathway

from contextlib import contextmanager


@contextmanager
def optional_imports(extra: str):
    try:
        yield
    except ImportError as e:
        raise ImportError(f"{e}. Consider installing 'pathway[{extra}]'")

View on GitHub (pinned to fa2f74a464)

Solutions

1. Install the suggested extra: pip install 'pathway[weaviate]' (or whichever extra the message names).
2. Or install the underlying package directly, e.g. pip install weaviate-client, if you do not want the full extra bundle.
3. Pin the extra in requirements.txt / pyproject.toml so CI and teammates get it automatically.

Example fix

# before
pip install pathway
# ... ImportError: No module named 'weaviate_client'. Consider installing 'pathway[weaviate]'

# after
pip install 'pathway[weaviate]'

def extra_installed(extra):
    try:
        import importlib.util
        return importlib.util.find_spec(_extra_modules.get(extra, extra)) is not None
    except ImportError:
        return False

try:
    pw.io.weaviate.write(...)
except ImportError as e:
    if "Consider installing" in str(e):
        raise SystemExit(f"Missing optional dependency: {e}. Run: pip install 'pathway[weaviate]'") from e
    raise

When it happens

Trigger: Using a Pathway connector or module that depends on an optional package (weaviate client, tantivy, usearch, etc.) without having installed the corresponding `pathway[extra]` bundle; the with optional_imports('extra'): block around those imports converts the ImportError.

Common situations: Installing plain `pip install pathway` and then calling pw.io.weaviate.write or BM25 indexing; a fresh environment/CI image built from a trimmed requirements list; a teammate's lockfile that dropped an optional dependency.

Related errors

• LEANN connector requires the `leann` package. Please visit h
• Failed to install dependencies
• Column {pseudocolumn} has to contain integers only.
• Column {api.TIME_PSEUDOCOLUMN} cannot contain negative times
• Column {api.DIFF_PSEUDOCOLUMN} can only have 1 and -1 values

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/2fa8bba951e83cdc. Report an issue: GitHub.