chroma-core/chroma · error · ValueError

The {api_key_env_var} environment variable is not set.

Error message

The {api_key_env_var} environment variable is not set.

What it means

MistralEmbeddingFunction reads os.getenv(api_key_env_var) (default 'MISTRAL_API_KEY') in __init__ and raises this ValueError when the variable is empty/unset — there is no api_key constructor parameter at all, the env var is the only key-injection path. The Mistral embeddings API requires a bearer token, so the EF refuses to construct without one.

Source

Thrown at chromadb/utils/embedding_functions/mistral_embedding_function.py:31

    ):
        """
        Initialize the MistralEmbeddingFunction.

        Args:
            model (str): The name of the model to use for text embeddings.
            api_key_env_var (str): The environment variable name for the Mistral API key.
        """
        try:
            from mistralai import Mistral
        except ImportError:
            raise ValueError(
                "The mistralai python package is not installed. Please install it with `pip install mistralai`"
            )
        self.model = model
        self.api_key_env_var = api_key_env_var
        self.api_key = os.getenv(api_key_env_var)
        if not self.api_key:
            raise ValueError(f"The {api_key_env_var} environment variable is not set.")
        self.client = Mistral(api_key=self.api_key)

    def __call__(self, input: Documents) -> Embeddings:
        """
        Get the embeddings for a list of texts.

        Args:
            input (Documents): A list of texts to get embeddings for.
        """
        if not all(isinstance(item, str) for item in input):
            raise ValueError("Mistral only supports text documents, not images")
        output = self.client.embeddings.create(
            model=self.model,
            inputs=input,
        )

        # Extract embeddings from the response
        return [np.array(data.embedding) for data in output.data]

View on GitHub (pinned to aecdd12c8a)

Solutions

  1. export MISTRAL_API_KEY=... in the launching environment
  2. For a custom var name: MistralEmbeddingFunction(model='mistral-embed', api_key_env_var='MY_MISTRAL_KEY')
  3. Load .env before construction: from dotenv import load_dotenv; load_dotenv()
  4. Preflight: python -c "import os; assert os.getenv('MISTRAL_API_KEY')"

Example fix

# before
from chromadb.utils.embedding_functions import MistralEmbeddingFunction
ef = MistralEmbeddingFunction(model="mistral-embed")  # ValueError: env var not set

# after
import os
from dotenv import load_dotenv
load_dotenv()
assert os.getenv("MISTRAL_API_KEY"), "MISTRAL_API_KEY missing"
ef = MistralEmbeddingFunction(model="mistral-embed")
Defensive patterns

Strategy: validation

Validate before calling

import os

if not os.getenv("MISTRAL_API_KEY"):
    raise SystemExit("MISTRAL_API_KEY is required for MistralEmbeddingFunction")

from chromadb.utils.embedding_functions import MistralEmbeddingFunction
ef = MistralEmbeddingFunction(model="mistral-embed")

Try / catch

try:
    ef = MistralEmbeddingFunction(model="mistral-embed")
except ValueError as e:
    if "environment variable is not set" in str(e):
        raise RuntimeError("Set MISTRAL_API_KEY in the process environment") from e
    raise

Prevention

When it happens

Trigger: MistralEmbeddingFunction(model='mistral-embed') with MISTRAL_API_KEY unset; running under docker/systemd/github-actions where the secret env var was not declared; setting the var with a typo (e.g. MISTRALAPI_KEY) or only in the interactive shell that did not launch the process.

Common situations: CI jobs missing the secret; containers without env passthrough; .env loaded after EF construction; keys defined per-project but the app runs in another directory.

Related errors

AI-assisted analysis of chroma-core/chroma@aecdd12c8a (2026-08-16). Data as JSON: /api/errors/829c56ebd3f1695b. Report an issue: GitHub.