keras-team/keras · error · ValueError

Invalid `output_size`. Expected length 2 (H, W). Got: output

Error message

Invalid `output_size`. Expected length 2 (H, W). Got: output_size={output_size}

What it means

Error "Invalid `output_size`. Expected length 2 (H, W). Got: output_size={output_size}" thrown in keras-team/keras.

Source

Thrown at keras/src/ops/image.py:1218

def _reconstruct_patches_2d(
    patches,
    size,
    output_size,
    strides=None,
    padding="valid",
    data_format=None,
):
    if isinstance(size, int):
        size = (size, size)
    if len(size) != 2:
        raise ValueError(
            "Invalid `size`. Expected length 2 for 2D reconstruction. "
            f"Got: size={size}"
        )
    if len(output_size) != 2:
        raise ValueError(
            "Invalid `output_size`. Expected length 2 (H, W). "
            f"Got: output_size={output_size}"
        )
    if padding not in ("same", "valid"):
        raise ValueError(
            f"Invalid `padding`. Expected 'same' or 'valid'. Got: {padding}"
        )
    _validate_reconstruct_strides(size, strides, "reconstruct_patches")
    data_format = backend.standardize_data_format(data_format)
    if data_format == "channels_first":
        # Reconstruct in channels_last layout, then move channels back.
        # Patches are (flat, gH, gW) unbatched or (B, flat, gH, gW) batched.
        if len(patches.shape) == 3:
            patches = backend.numpy.transpose(patches, axes=(1, 2, 0))
        elif len(patches.shape) == 4:
            patches = backend.numpy.transpose(patches, axes=(0, 2, 3, 1))
        else:
            raise ValueError(

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/ops/image.py:1218 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/9a876cad07206e5a. Report an issue: GitHub.