keras-team/keras · error · ValueError

For 1D input, `output_size` tuple must have length 1. Receiv

Error message

For 1D input, `output_size` tuple must have length 1. Received: {output_size}

What it means

Error "For 1D input, `output_size` tuple must have length 1. Received: {output_size}" thrown in keras-team/keras.

Source

Thrown at keras/src/layers/pooling/adaptive_max_pooling1d.py:54

            `(batch_size, output_length, channels)`
        - If `data_format="channels_first"`:
            `(batch_size, channels, output_length)`

    Examples:
        >>> import numpy as np
        >>> input_seq = np.random.rand(1, 64, 3)
        >>> layer = AdaptiveMaxPooling1D(output_size=32)
        >>> output_seq = layer(input_seq)
        >>> output_seq.shape
        (1, 32, 3)
    """

    def __init__(self, output_size, data_format=None, **kwargs):
        if isinstance(output_size, int):
            output_size = (output_size,)
        elif isinstance(output_size, (tuple, list)):
            if len(output_size) != 1:
                raise ValueError(
                    f"For 1D input, `output_size` tuple must have length 1. "
                    f"Received: {output_size}"
                )
            output_size = tuple(output_size)
        else:
            raise TypeError(
                f"`output_size` must be an integer or tuple of 1 integer. "
                f"Received: {output_size} of type {type(output_size)}"
            )

        super().__init__(output_size, data_format, **kwargs)

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/layers/pooling/adaptive_max_pooling1d.py:54 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of keras-team/keras@7a34a03db6 (2026-08-25). Data as JSON: /api/errors/4b33870528f5968a. Report an issue: GitHub.