keras-team/keras · error · ValueError

Unknown {printable_module_name}: '{class_name}'. Please ensu

Error message

Unknown {printable_module_name}: '{class_name}'. Please ensure you are using a `keras.utils.custom_object_scope` and that this object is included in the scope. See https://www.tensorflow.org/guide/keras/save_and_serialize#registering_the_custom_object for details.

What it means

Error "Unknown {printable_module_name}: '{class_name}'. Please ensure you are using a `keras.utils.custom_object_scope` and that this object is included in the scope. See https://www.tensorflow.org/guide/keras/save_and_serialize#registering_the_custom_object for details." thrown in keras-team/keras.

Source

Thrown at keras/src/legacy/saving/serialization.py:353

):
    """Returns the class name and config for a serialized keras object."""

    if (
        not isinstance(config, dict)
        or "class_name" not in config
        or "config" not in config
    ):
        raise ValueError(
            f"Improper config format for {config}. "
            "Expecting python dict contains `class_name` and `config` as keys"
        )

    class_name = config["class_name"]
    cls = object_registration.get_registered_object(
        class_name, custom_objects, module_objects
    )
    if cls is None:
        raise ValueError(
            f"Unknown {printable_module_name}: '{class_name}'. "
            "Please ensure you are using a `keras.utils.custom_object_scope` "
            "and that this object is included in the scope. See "
            "https://www.tensorflow.org/guide/keras/save_and_serialize"
            "#registering_the_custom_object for details."
        )

    cls_config = config["config"]
    # Check if `cls_config` is a list. If it is a list, return the class and the
    # associated class configs for recursively deserialization. This case will
    # happen on the old version of sequential model (e.g. `keras_version` ==
    # "2.0.6"), which is serialized in a different structure, for example
    # "{'class_name': 'Sequential',
    #   'config': [{'class_name': 'Embedding', 'config': ...}, {}, ...]}".
    if isinstance(cls_config, list):
        return (cls, cls_config)

    deserialized_objects = {}

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/legacy/saving/serialization.py:353 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/382ee8163b61bd3e. Report an issue: GitHub.