{"record":{"id":"765be2e74ec4981a","repo":"keras-team/keras","slug":"backend-backend-backend-must-implement-the-t","errorCode":null,"errorMessage":"Backend '{backend.backend()}' must implement the Trainer class.","messagePattern":"Backend '(.+?)' must implement the Trainer class\\.","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"keras/src/models/model.py","lineNumber":37,"sourceCode":"from keras.src.trainers import trainer as base_trainer\nfrom keras.src.utils import io_utils\nfrom keras.src.utils import summary_utils\nfrom keras.src.utils import traceback_utils\n\nif backend.backend() == \"tensorflow\":\n    from keras.src.backend.tensorflow.trainer import (\n        TensorFlowTrainer as Trainer,\n    )\nelif backend.backend() == \"jax\":\n    from keras.src.backend.jax.trainer import JAXTrainer as Trainer\nelif backend.backend() == \"torch\":\n    from keras.src.backend.torch.trainer import TorchTrainer as Trainer\nelif backend.backend() == \"numpy\":\n    from keras.src.backend.numpy.trainer import NumpyTrainer as Trainer\nelif backend.backend() == \"openvino\":\n    from keras.src.backend.openvino.trainer import OpenVINOTrainer as Trainer\nelse:\n    raise RuntimeError(\n        f\"Backend '{backend.backend()}' must implement the Trainer class.\"\n    )\n\n\n@keras_export([\"keras.Model\", \"keras.models.Model\"])\nclass Model(Trainer, base_trainer.Trainer, Layer):\n    \"\"\"A model grouping layers into an object with training/inference features.\n\n    There are three ways to instantiate a `Model`:\n\n    ## With the \"Functional API\"\n\n    You start from `Input`,\n    you chain layer calls to specify the model's forward pass,\n    and finally, you create your model from inputs and outputs:\n\n    ```python\n    inputs = keras.Input(shape=(37,))","sourceCodeStart":19,"sourceCodeEnd":55,"githubUrl":"https://github.com/keras-team/keras/blob/7a34a03db60bf60042242d6a556fc3be119046a5/keras/src/models/model.py#L19-L55","documentation":"Error \"Backend '{backend.backend()}' must implement the Trainer class.\" thrown in keras-team/keras.","triggerScenarios":"Thrown at keras/src/models/model.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"}