keras-team/keras · error · ValueError

Unknown {printable_module_name}: '{object_name}'. Please ens

Error message

Unknown {printable_module_name}: '{object_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}: '{object_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:531

        return deserialized_obj

    elif isinstance(identifier, str):
        object_name = identifier
        if custom_objects and object_name in custom_objects:
            obj = custom_objects.get(object_name)
        elif (
            object_name
            in object_registration._THREAD_LOCAL_CUSTOM_OBJECTS.__dict__
        ):
            obj = object_registration._THREAD_LOCAL_CUSTOM_OBJECTS.__dict__[
                object_name
            ]
        elif object_name in object_registration._GLOBAL_CUSTOM_OBJECTS:
            obj = object_registration._GLOBAL_CUSTOM_OBJECTS[object_name]
        else:
            obj = module_objects.get(object_name)
            if obj is None:
                raise ValueError(
                    f"Unknown {printable_module_name}: '{object_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."
                )

        # Classes passed by name are instantiated with no args, functions are
        # returned as-is.
        if inspect.isclass(obj):
            return obj()
        return obj
    elif inspect.isfunction(identifier):
        # If a function has already been deserialized, return as is.
        return identifier
    else:
        raise ValueError(

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/legacy/saving/serialization.py:531 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/7bbe0f49cbf26e24. Report an issue: GitHub.