langchain-ai/langchain · error · ValueError

Batch size must be a positive integer, got {size}.

Error message

Batch size must be a positive integer, got {size}.

What it means

Error "Batch size must be a positive integer, got {size}." thrown in langchain-ai/langchain.

Source

Thrown at libs/core/langchain_core/utils/iter.py:223

def batch_iterate(size: int | None, iterable: Iterable[T]) -> Iterator[list[T]]:
    """Utility batching function.

    Args:
        size: The size of the batch.

            If `None`, returns a single batch.
        iterable: The iterable to batch.

    Yields:
        The batches of the iterable.

    Raises:
        ValueError: If `size` is not `None` and is not a positive integer.
    """
    if size is not None and size <= 0:
        msg = f"Batch size must be a positive integer, got {size}."
        raise ValueError(msg)
    it = iter(iterable)
    while True:
        chunk = list(islice(it, size))
        if not chunk:
            return
        yield chunk

View on GitHub (pinned to e32fa9a52e)

Solutions

1. Pass a batch size that is a positive integer (>= 1).
2. If the size comes from configuration, validate it before calling batching.

Example fix

for chunk in batch_iterate(size=max(1, batch_size), iterable=items): ...

When it happens

Trigger: Raised when a batch() helper is called with a batch size that is not a positive integer (zero or negative).

Common situations: See trigger scenarios.

AI-assisted analysis of langchain-ai/langchain@e32fa9a52e (2026-08-14). Data as JSON: /api/errors/aa67403bf336f8f8. Report an issue: GitHub.