{"record":{"id":"1d2c64a7587f715e","repo":"huggingface/transformers","slug":"no-hyperparameter-search-backend-available-n-to","errorCode":null,"errorMessage":"No hyperparameter search backend available.\\n - To install {backend.name} run {backend.pip_install()}","messagePattern":"No hyperparameter search backend available\\.\\\\n - To install (.+?) run (.+?)","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"src/transformers/hyperparameter_search.py","lineNumber":117,"sourceCode":"    def default_hp_space(self, trial):\n        return default_hp_space_wandb(trial)\n\n\nALL_HYPERPARAMETER_SEARCH_BACKENDS = {\n    HPSearchBackend(backend.name): backend for backend in [OptunaBackend, RayTuneBackend, WandbBackend]\n}\n\n\ndef default_hp_search_backend() -> str:\n    available_backends = [backend for backend in ALL_HYPERPARAMETER_SEARCH_BACKENDS.values() if backend.is_available()]\n    if len(available_backends) > 0:\n        name = available_backends[0].name\n        if len(available_backends) > 1:\n            logger.info(\n                f\"{len(available_backends)} hyperparameter search backends available. Using {name} as the default.\"\n            )\n        return name\n    raise RuntimeError(\n        \"No hyperparameter search backend available.\\n\"\n        + \"\\n\".join(\n            f\" - To install {backend.name} run {backend.pip_install()}\"\n            for backend in ALL_HYPERPARAMETER_SEARCH_BACKENDS.values()\n        )\n    )\n","sourceCodeStart":99,"sourceCodeEnd":124,"githubUrl":"https://github.com/huggingface/transformers/blob/a597f974857b3d92939971296bc0deb93d33d780/src/transformers/hyperparameter_search.py#L99-L124","documentation":"Error \"No hyperparameter search backend available.\\n - To install {backend.name} run {backend.pip_install()}\" thrown in huggingface/transformers.","triggerScenarios":"Raised in default_hp_search_backend when no supported hyperparameter search backend is installed at all.","commonSituations":"Running hyperparameter_search without installing optuna, ray[tune], sigopt, or wandb.","solutions":["Install one of the supported HPO backends (e.g. `pip install optuna` or `pip install ray[tune]`).","Remove the hyperparameter search call if no backend is desired."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"a597f974857b3d92939971296bc0deb93d33d780","analyzedAt":"2026-08-14T18:24:08.354Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}