keras-team/keras · error · ValueError

Argument `output` must be at least rank 1. Received: output.

Error message

Argument `output` must be at least rank 1. Received: output.shape={output.shape}

What it means

Error "Argument `output` must be at least rank 1. Received: output.shape={output.shape}" thrown in keras-team/keras.

Source

Thrown at keras/src/backend/numpy/nn.py:893

        )

    if from_logits:
        log_prob = log_softmax(output, axis=axis)
    else:
        output = output / np.sum(output, axis, keepdims=True)
        output = np.clip(output, backend.epsilon(), 1.0 - backend.epsilon())
        log_prob = np.log(output)
    return -np.sum(target * log_prob, axis=axis)


def sparse_categorical_crossentropy(target, output, from_logits=False, axis=-1):
    target = np.array(target, dtype="int32")
    output = np.array(output)
    if len(target.shape) == len(output.shape) and target.shape[-1] == 1:
        target = np.squeeze(target, axis=-1)

    if len(output.shape) < 1:
        raise ValueError(
            "Argument `output` must be at least rank 1. "
            "Received: "
            f"output.shape={output.shape}"
        )
    if target.shape != output.shape[:-1]:
        raise ValueError(
            "Arguments `target` and `output` must have the same shape "
            "up until the last dimension: "
            f"target.shape={target.shape}, output.shape={output.shape}"
        )
    if from_logits:
        log_prob = log_softmax(output, axis=axis)
    else:
        output = output / np.sum(output, axis, keepdims=True)
        output = np.clip(output, backend.epsilon(), 1.0 - backend.epsilon())
        log_prob = np.log(output)
    target = one_hot(target, output.shape[axis], axis=axis)
    return -np.sum(target * log_prob, axis=axis)

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/backend/numpy/nn.py:893 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/eafb9c4fb71c3889. Report an issue: GitHub.