keras-team/keras · error · ValueError

Invalid value for argument `output_mode`. Expected one of {'

Error message

Invalid value for argument `output_mode`. Expected one of {'dict', 'concat'}. Received: output_mode={output_mode}

What it means

Error "Invalid value for argument `output_mode`. Expected one of {'dict', 'concat'}. Received: output_mode={output_mode}" thrown in keras-team/keras.

Source

Thrown at keras/src/layers/preprocessing/feature_space.py:435

                        raise ValueError(
                            "When specifying `crosses`, the argument "
                            "`crossing_dim` "
                            "(dimensionality of the crossing space) "
                            "should be specified as well."
                        )
                    for key in cross:
                        if key not in feature_set:
                            raise ValueError(
                                "All features referenced "
                                "in the `crosses` argument "
                                "should be present in the `features` dict. "
                                f"Received unknown features: {cross}"
                            )
                    self.crosses.append(Cross(cross, crossing_dim=crossing_dim))
        self.crosses_by_name = {cross.name: cross for cross in self.crosses}

        if output_mode not in {"dict", "concat"}:
            raise ValueError(
                "Invalid value for argument `output_mode`. "
                "Expected one of {'dict', 'concat'}. "
                f"Received: output_mode={output_mode}"
            )
        self.output_mode = output_mode

        self.inputs = {
            name: self._feature_to_input(name, value)
            for name, value in self.features.items()
        }
        self.preprocessors = {
            name: value.preprocessor for name, value in self.features.items()
        }
        self.encoded_features = None
        self.crossers = {
            cross.name: self._cross_to_crosser(cross) for cross in self.crosses
        }
        self.one_hot_encoders = {}

View on GitHub (pinned to 7a34a03db6)

When it happens

Trigger: Thrown at keras/src/layers/preprocessing/feature_space.py:435 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/bb6f1bf6e33d6d9d. Report an issue: GitHub.