{"record":{"id":"c77dfc30a8cc5e97","repo":"keras-team/keras","slug":"a-subtract-layer-should-be-called-on-exactly-2-i","errorCode":null,"errorMessage":"A `Subtract` layer should be called on exactly 2 inputs. Received: input_shape={input_shape}","messagePattern":"A `Subtract` layer should be called on exactly 2 inputs\\. Received: input_shape=(.+?)","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"keras/src/layers/merging/subtract.py","lineNumber":37,"sourceCode":"    >>> y = keras.layers.Subtract()([x1, x2])\n\n    Usage in a Keras model:\n\n    >>> input1 = keras.layers.Input(shape=(16,))\n    >>> x1 = keras.layers.Dense(8, activation='relu')(input1)\n    >>> input2 = keras.layers.Input(shape=(32,))\n    >>> x2 = keras.layers.Dense(8, activation='relu')(input2)\n    >>> # equivalent to `subtracted = keras.layers.subtract([x1, x2])`\n    >>> subtracted = keras.layers.Subtract()([x1, x2])\n    >>> out = keras.layers.Dense(4)(subtracted)\n    >>> model = keras.models.Model(inputs=[input1, input2], outputs=out)\n\n    \"\"\"\n\n    def build(self, input_shape):\n        super().build(input_shape)\n        if len(input_shape) != 2:\n            raise ValueError(\n                \"A `Subtract` layer should be called on exactly 2 inputs. \"\n                f\"Received: input_shape={input_shape}\"\n            )\n\n    def _merge_function(self, inputs):\n        if len(inputs) != 2:\n            raise ValueError(\n                \"A `Subtract` layer should be called on exactly 2 inputs. \"\n                f\"Received: inputs={inputs}\"\n            )\n        return ops.subtract(inputs[0], inputs[1])\n\n\n@keras_export(\"keras.layers.subtract\")\ndef subtract(inputs, **kwargs):\n    \"\"\"Functional interface to the `keras.layers.Subtract` layer.\n\n    Args:","sourceCodeStart":19,"sourceCodeEnd":55,"githubUrl":"https://github.com/keras-team/keras/blob/7a34a03db60bf60042242d6a556fc3be119046a5/keras/src/layers/merging/subtract.py#L19-L55","documentation":"Error \"A `Subtract` layer should be called on exactly 2 inputs. Received: input_shape={input_shape}\" thrown in keras-team/keras.","triggerScenarios":"Thrown at keras/src/layers/merging/subtract.py:37 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"7a34a03db60bf60042242d6a556fc3be119046a5","analyzedAt":"2026-08-25T21:25:25.994Z","schemaVersion":2},"datasetVersion":"2026-08-26T02:17:13.382Z"}