keras-team/keras · error · ValueError

The input '{input_tensor.name}' is not optional, but None wa

Error message

The input '{input_tensor.name}' is not optional, but None was passed. Please provide a valid tensor.

What it means

Error "The input '{input_tensor.name}' is not optional, but None was passed. Please provide a valid tensor." thrown in keras-team/keras.

Source

Thrown at keras/src/models/functional.py:221

        return input_shapes

    @property
    def output_shape(self):
        output_shapes = tree.map_structure(lambda x: x.shape, self.outputs)
        if isinstance(output_shapes, list) and len(output_shapes) == 1:
            return output_shapes[0]
        return output_shapes

    def _assert_input_compatibility(self, *args):
        flat_inputs = tree.flatten(args[0])
        for x, input_tensor in zip(flat_inputs, self._inputs):
            if x is None:
                input_layer = input_tensor._keras_history.operation
                if (
                    isinstance(input_layer, InputLayer)
                    and not input_layer.optional
                ):
                    raise ValueError(
                        (
                            f"The input '{input_tensor.name}' is not optional, "
                            "but None was passed. "
                            "Please provide a valid tensor."
                        )
                    )
        return super(Model, self)._assert_input_compatibility(*args)

    def _maybe_warn_inputs_struct_mismatch(self, inputs, raise_exception=False):
        try:
            # We first normalize to tuples before performing the check to
            # suppress warnings when encountering mismatched tuples and lists.
            tree.assert_same_structure(
                tree.lists_to_tuples(inputs),
                tree.lists_to_tuples(self._inputs_struct),
            )
        except:
            model_inputs_struct = tree.map_structure(

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/models/functional.py:221 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/5c740b11582bd225. Report an issue: GitHub.