{"record":{"id":"5fed53c743feffe8","repo":"VectifyAI/PageIndex","slug":"the-anthropic-backend-is-not-configured-exc","errorCode":null,"errorMessage":"The Anthropic backend is not configured: {exc}","messagePattern":"The Anthropic backend is not configured: (.+?)","errorType":"exception","errorClass":"PageIndexAPIError","httpStatus":null,"severity":"error","filePath":"pageindex/local_chat.py","lineNumber":908,"sourceCode":"    \"\"\"The backend client — the seam tests replace with a fake transport.\n    One client per backend: each construction pays ~45 ms of SSL-context\n    build and a cold connection pool. A backend whose values defeat\n    hashing constructs per call, as before.\"\"\"\n    import anthropic\n    kwargs = _sdk_backend(backend)\n    try:\n        key = tuple(sorted(\n            (k, tuple(sorted(v.items())) if isinstance(v, dict) else v)\n            for k, v in kwargs.items()))\n        hash(key)\n    except TypeError:\n        key = None\n    if key in _ANTHROPIC_CLIENTS:\n        return _ANTHROPIC_CLIENTS[key]\n    try:\n        client = anthropic.Anthropic(**kwargs)\n    except TypeError as exc:\n        raise PageIndexAPIError(\n            f\"The Anthropic backend is not configured: {exc}\") from exc\n    if key is not None and len(_ANTHROPIC_CLIENTS) < 8:\n        # ponytail: cache capped at 8 backends; the tail constructs per call.\n        # setdefault: never evict a client another thread may already hold.\n        client = _ANTHROPIC_CLIENTS.setdefault(key, client)\n    return client\n\n\ndef _anthropic_system(client, extra_system, block: Optional[str]) -> list[dict]:\n    \"\"\"System blocks: cache_control marks the stable managed prefix only\n    (the API allows 4 breakpoints total — the varying doc block and caller\n    blocks must not consume the budget); the doc block and caller system\n    content follow as their own blocks.\"\"\"\n    blocks = [{\"type\": \"text\",\n               \"text\": CHAT_HEADER + \"\\n\\n\" + _base_instructions(client),\n               \"cache_control\": {\"type\": \"ephemeral\"}}]\n    if block:\n        blocks.append({\"type\": \"text\", \"text\": block})","sourceCodeStart":890,"sourceCodeEnd":926,"githubUrl":"https://github.com/VectifyAI/PageIndex/blob/afb5e119766630af6014b04fe8b53357527bc05e/pageindex/local_chat.py#L890-L926","documentation":"Constructing the Anthropic client from your chat_backend/backend settings raised TypeError, meaning the backend dict contains arguments the Anthropic constructor doesn't accept (or invalid types for it). _anthropic_client() wraps the failure so you see which configuration is broken rather than a raw SDK traceback.","triggerScenarios":"Passing chat_backend={'backend': 'anthropic', 'model': '...', <unknown-kwarg>: ...} to messages(); any kwarg combo for which anthropic.Anthropic(**kwargs) raises TypeError (unknown parameter name, wrong type).","commonSituations":"Copying backend settings from an OpenAI-style config (e.g. base_url vs api_base, or engine-specific keys); typos in kwarg names; passing model config keys that belong on the request, not the client constructor.","solutions":["Read the wrapped message — it embeds the original TypeError naming the bad argument; remove or fix that key in chat_backend/backend","Compare your kwargs against anthropic.Anthropic's constructor signature (api_key, base_url, timeout, max_retries, ...)","Move request-level options (temperature, top_p, top_k, model) to the messages() call, not the backend dict"],"exampleFix":"# before\nclient.messages(prompt, chat_backend={'backend': 'anthropic', 'api_base': 'https://...'})\n# after\nclient.messages(prompt, chat_backend={'backend': 'anthropic', 'base_url': 'https://...'})","handlingStrategy":"validation","validationCode":"import inspect, anthropic\nvalid = set(inspect.signature(anthropic.Anthropic).parameters)\nbackend = {'backend': 'anthropic', 'model': 'claude-...'}\nbackend = {k: v for k, v in backend.items() if k in valid or k in ('backend', 'model')}","typeGuard":"def is_valid_backend(cfg: dict) -> bool:\n    return isinstance(cfg, dict) and set(cfg) <= {'backend', 'model', 'api_key', 'base_url', 'timeout', 'max_retries'}","tryCatchPattern":"try:\n    client.messages(\"hi\", chat_backend=cfg)\nexcept PageIndexAPIError as e:\n    if \"backend is not configured\" in str(e):\n        log.error(\"bad anthropic kwargs: %s\", cfg)\n    raise","preventionTips":["Keep backend dicts to documented keys only","Keep request-level params out of the client config","Log the backend dict when this fires"],"tags":["anthropic","config","backend","typeerror"],"backgroundTag":"invalid-client-configuration","analyzedSha":"afb5e119766630af6014b04fe8b53357527bc05e","analyzedAt":"2026-08-27T11:20:48.519Z","schemaVersion":2},"datasetVersion":"2026-08-27T13:17:12.746Z"}