mem0ai/mem0 · error · ImportError

The 'pymilvus' library is required. Please install it using

Error message

The 'pymilvus' library is required. Please install it using 'pip install pymilvus'.

What it means

Module-level ImportError raised when pymilvus is missing. The Milvus vector store imports pymilvus symbols (MilvusClient, CollectionSchema, ...) at module import, so configuring provider 'milvus' in an environment without pymilvus fails immediately.

Source

Thrown at mem0/vector_stores/milvus.py:13

import logging
import re
from typing import Dict, Optional

from pydantic import BaseModel

from mem0.configs.vector_stores.milvus import MetricType
from mem0.vector_stores.base import VectorStoreBase

try:
    import pymilvus  # noqa: F401
except ImportError:
    raise ImportError("The 'pymilvus' library is required. Please install it using 'pip install pymilvus'.")

from pymilvus import (
    CollectionSchema,
    DataType,
    FieldSchema,
    Function,
    FunctionType,
    MilvusClient,
)

logger = logging.getLogger(__name__)


class OutputData(BaseModel):
    id: Optional[str]  # memory id
    score: Optional[float]  # distance
    payload: Optional[Dict]  # metadata

View on GitHub (pinned to 001c235229)

Solutions

1. pip install pymilvus
2. Add pymilvus to the deployment image's dependency list
3. Verify with 'python -c "import pymilvus"' before switching the provider

Example fix

# before
# MemoryConfig vector_store.provider='milvus' -> ImportError

# after
# shell: pip install pymilvus
from mem0.vector_stores.milvus import Milvus

try:
    import pymilvus  # noqa
    HAVE_MILVUS = True
except ImportError:
    HAVE_MILVUS = False

try:
    from mem0.vector_stores.milvus import Milvus
except ImportError as e:
    raise RuntimeError('Run: pip install pymilvus') from e

When it happens

Trigger: Setting provider='milvus' in vector_store config, or importing mem0.vector_stores.milvus, without pymilvus installed.

Common situations: Base mem0ai install without extras; CI images trimmed of optional deps; local dev against Qdrant/FAISS then deploying the same image pointed at Milvus.

Related errors

• The 'upstash_vector' library is required. Please install it
• The 'pymochow' library is required. Please install it using
• Apache Cassandra vector store requires cassandra-driver. Ple
• The 'chromadb' library is required. Please install it using
• Elasticsearch requires extra dependencies. Install with `pip

AI-assisted analysis of mem0ai/mem0@001c235229 (2026-08-15). Data as JSON: /api/errors/760a9b2c877f62b5. Report an issue: GitHub.