keras-team/keras · error · ValueError

Unsupported value `sparse=True` with numpy backend

Error message

Unsupported value `sparse=True` with numpy backend

What it means

Error "Unsupported value `sparse=True` with numpy backend" thrown in keras-team/keras.

Source

Thrown at keras/src/backend/numpy/nn.py:822

        include_batch_and_channels=False,
    )

    return np.array(
        jax.lax.conv_transpose(
            inputs,
            kernel if is_tensor(kernel) else kernel.numpy(),
            strides,
            padding=padding_values,
            rhs_dilation=dilation_rate,
            dimension_numbers=dimension_numbers,
            transpose_kernel=True,
        )
    )


def one_hot(x, num_classes, axis=-1, dtype=None, sparse=False):
    if sparse:
        raise ValueError("Unsupported value `sparse=True` with numpy backend")
    if dtype is None:
        dtype = "float32"
    x = convert_to_tensor(x)
    input_shape = x.shape

    x = x.reshape(-1)
    if not num_classes:
        num_classes = np.max(x) + 1

    batch_size = x.shape[0]
    categorical = np.zeros((batch_size, num_classes), dtype=dtype)
    valid_indices = x >= 0
    categorical[np.arange(batch_size)[valid_indices], x[valid_indices]] = 1

    # First, reshape the array with the extra dimension at the end
    output_shape = input_shape + (num_classes,)
    categorical = np.reshape(categorical, output_shape)

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/backend/numpy/nn.py:822 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/372a471e9f2aa870. Report an issue: GitHub.