BerriAI/litellm · error · ImportError

backoff is not installed. Please install it via 'pip install

Error message

backoff is not installed. Please install it via 'pip install backoff'

What it means

Module-level import guard in litellm/proxy/utils.py: the optional 'backoff' dependency is not installed in the environment. Email-sending callbacks rely on it for retry/backoff, so the proxy module refuses to load at import time until 'pip install backoff' is run.

Source

Thrown at litellm/proxy/utils.py:67

    from litellm_enterprise.enterprise_callbacks.send_emails.resend_email import (
        ResendEmailLogger,
    )
    from litellm_enterprise.enterprise_callbacks.send_emails.sendgrid_email import (
        SendGridEmailLogger,
    )
    from litellm_enterprise.enterprise_callbacks.send_emails.smtp_email import (
        SMTPEmailLogger,
    )
except ImportError:
    BaseEmailLogger = None
    SendGridEmailLogger = None
    SMTPEmailLogger = None
    ResendEmailLogger = None

try:
    import backoff
except ImportError:
    raise ImportError("backoff is not installed. Please install it via 'pip install backoff'")

from fastapi import HTTPException, status

import litellm
import litellm.litellm_core_utils
import litellm.litellm_core_utils.litellm_logging
from litellm import (
    EmbeddingResponse,
    ImageResponse,
    ModelResponse,
    ModelResponseStream,
    Router,
)
from litellm._logging import _redact_string, verbose_proxy_logger
from litellm._service_logger import ServiceLogging, ServiceTypes
from litellm.caching.caching import DualCache, RedisCache
from litellm.caching.dual_cache import LimitedSizeOrderedDict
from litellm.exceptions import RejectedRequestError, SensitiveDataRouteException

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Install the backoff package: pip install backoff.

When it happens

Trigger: Thrown at litellm/proxy/utils.py:67 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/c29220d6851495a0. Report an issue: GitHub.