{"record":{"id":"bcdb4d0784107e09","repo":"keras-team/keras","slug":"backend-backend-backend-must-implement-a-lay","errorCode":null,"errorMessage":"Backend '{backend.backend()}' must implement a layer mixin class.","messagePattern":"Backend '(.+?)' must implement a layer mixin class\\.","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"keras/src/layers/layer.py","lineNumber":65,"sourceCode":"from keras.src.ops.operation import Operation\nfrom keras.src.quantizers.quantization_config import validate_and_resolve_config\nfrom keras.src.utils import python_utils\nfrom keras.src.utils import summary_utils\nfrom keras.src.utils import traceback_utils\nfrom keras.src.utils import tracking\n\nif backend.backend() == \"tensorflow\":\n    from keras.src.backend.tensorflow.layer import TFLayer as BackendLayer\nelif backend.backend() == \"jax\":\n    from keras.src.backend.jax.layer import JaxLayer as BackendLayer\nelif backend.backend() == \"torch\":\n    from keras.src.backend.torch.layer import TorchLayer as BackendLayer\nelif backend.backend() == \"numpy\":\n    from keras.src.backend.numpy.layer import NumpyLayer as BackendLayer\nelif backend.backend() == \"openvino\":\n    from keras.src.backend.openvino.layer import OpenvinoLayer as BackendLayer\nelse:\n    raise RuntimeError(\n        f\"Backend '{backend.backend()}' must implement a layer mixin class.\"\n    )\n\n\n@keras_export([\"keras.Layer\", \"keras.layers.Layer\"])\nclass Layer(BackendLayer, Operation):\n    \"\"\"This is the class from which all layers inherit.\n\n    A layer is a callable object that takes as input one or more tensors and\n    that outputs one or more tensors. It involves *computation*, defined\n    in the `call()` method, and a *state* (weight variables). State can be\n    created:\n\n    * in `__init__()`, for instance via `self.add_weight()`;\n    * in the optional `build()` method, which is invoked by the first\n      `__call__()` to the layer, and supplies the shape(s) of the input(s),\n      which may not have been known at initialization time.\n","sourceCodeStart":47,"sourceCodeEnd":83,"githubUrl":"https://github.com/keras-team/keras/blob/7a34a03db60bf60042242d6a556fc3be119046a5/keras/src/layers/layer.py#L47-L83","documentation":"Error \"Backend '{backend.backend()}' must implement a layer mixin class.\" thrown in keras-team/keras.","triggerScenarios":"Thrown at keras/src/layers/layer.py:65 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"}