mem0ai/mem0 · error · ImportError

zeroentropy package is required for ZeroEntropyReranker…

Error message

zeroentropy package is required for ZeroEntropyReranker. Install with: pip install zeroentropy

What it means

ZeroEntropyReranker raises ImportError when the zeroentropy SDK is absent (guarded by ZERO_ENTROPY_AVAILABLE). ZeroEntropy is a commercial reranking service ('zerank-1'), and its client is an optional dependency not installed with core mem0. The failure occurs at construction, before any API key check or network call.

Solutions

pip install zeroentropy in the mem0 runtime environment
Add it to your requirements/pyproject alongside mem0 so installs stay reproducible
If unneeded, remove the reranker block or switch to a provider whose deps you already carry

Example fix

# before
config = {"reranker": {"provider": "zeroentropy", "config": {"model": "zerank-1"}}}
# ImportError

# after
# pip install zeroentropy
config = {"reranker": {"provider": "zeroentropy", "config": {"model": "zerank-1", "api_key": os.environ["ZERO_ENTROPY_API_KEY"]}}}

Defensive patterns

Strategy: validation

Validate before calling

import importlib.util
if importlib.util.find_spec("zeroentropy") is None:
    raise RuntimeError("install zeroentropy SDK before enabling the zeroentropy reranker")

Try / catch

try:
    reranker = ZeroEntropyReranker(cfg)
except ImportError:
    reranker = None  # or fall back to another provider

Prevention

List every optional provider SDK your config references in requirements
Run a dependency manifest check in CI against your mem0 config
Remove reranker configs you do not use

When it happens

Trigger: Configuring reranker={'provider':'zeroentropy', ...} without `pip install zeroentropy`; copying a config from ZeroEntropy's docs into an env that lacks their SDK; adding the provider typo-free but forgetting the install step.

Common situations: Evaluating commercial rerankers for quality; deploying configs authored on another machine; CI environments built from minimal requirements files that never listed zeroentropy.

Related errors

AI-assisted analysis of mem0ai/mem0@001c235229 (2026-08-15). Data as JSON: /api/errors/adbe2b019395a890. Report an issue: GitHub.

Appendix: source

Thrown at mem0/reranker/zero_entropy_reranker.py:27

    ZERO_ENTROPY_AVAILABLE = True
except ImportError:
    ZERO_ENTROPY_AVAILABLE = False

logger = logging.getLogger(__name__)


class ZeroEntropyReranker(BaseReranker):
    """Zero Entropy-based reranker implementation."""
    
    def __init__(self, config):
        """
        Initialize Zero Entropy reranker.
        
        Args:
            config: ZeroEntropyRerankerConfig object with configuration parameters
        """
        if not ZERO_ENTROPY_AVAILABLE:
            raise ImportError("zeroentropy package is required for ZeroEntropyReranker. Install with: pip install zeroentropy")
        
        self.config = config
        self.api_key = config.api_key or os.getenv("ZERO_ENTROPY_API_KEY")
        if not self.api_key:
            raise ValueError("Zero Entropy API key is required. Set ZERO_ENTROPY_API_KEY environment variable or pass api_key in config.")
            
        self.model = config.model or "zerank-1"
        
        # Initialize Zero Entropy client
        if self.api_key:
            self.client = ZeroEntropy(api_key=self.api_key)
        else:
            self.client = ZeroEntropy()  # Will use ZERO_ENTROPY_API_KEY from environment
        
    def rerank(self, query: str, documents: List[Dict[str, Any]], top_k: int = None) -> List[Dict[str, Any]]:
        """
        Rerank documents using Zero Entropy's rerank API.

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