keras-team/keras · error · ValueError

If imagenet weights are being loaded, alpha must be one of `

Error message

If imagenet weights are being loaded, alpha must be one of `0.35`, `0.50`, `0.75`, `1.0`, `1.3` or `1.4` only; Received `alpha={alpha}`

What it means

Error "If imagenet weights are being loaded, alpha must be one of `0.35`, `0.50`, `0.75`, `1.0`, `1.3` or `1.4` only; Received `alpha={alpha}`" thrown in keras-team/keras.

Source

Thrown at keras/src/applications/mobilenet_v2.py:228

    input_shape = imagenet_utils.obtain_input_shape(
        input_shape,
        default_size=default_size,
        min_size=32,
        data_format=backend.image_data_format(),
        require_flatten=include_top,
        weights=weights,
    )

    if backend.image_data_format() == "channels_last":
        row_axis, col_axis = (0, 1)
    else:
        row_axis, col_axis = (1, 2)
    rows = input_shape[row_axis]
    cols = input_shape[col_axis]

    if weights == "imagenet":
        if alpha not in [0.35, 0.50, 0.75, 1.0, 1.3, 1.4]:
            raise ValueError(
                "If imagenet weights are being loaded, "
                "alpha must be one of `0.35`, `0.50`, `0.75`, "
                "`1.0`, `1.3` or `1.4` only;"
                f" Received `alpha={alpha}`"
            )

        if rows != cols or rows not in [96, 128, 160, 192, 224]:
            rows = 224
            warnings.warn(
                "`input_shape` is undefined or non-square, "
                "or `rows` is not in [96, 128, 160, 192, 224]. "
                "Weights for input shape (224, 224) will be "
                "loaded as the default.",
                stacklevel=2,
            )

    if input_tensor is None:
        img_input = layers.Input(shape=input_shape)

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/applications/mobilenet_v2.py:228 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/cfa0454be1a37b78. Report an issue: GitHub.