BerriAI/litellm · error · ValueError

Configuration validation failed

Error message

Configuration validation failed:
{all_error_messages}

What it means

During Prometheus metrics setup, litellm parses every metric/label group config into parsed_configs, validates them all with _validate_all_configurations, and if any errors were collected it pretty-prints them (rich panels/tables) and raises this ValueError joining all error messages. The raise aborts label-filter construction, which normally means the prometheus callback fails to initialize and, in the proxy, startup dies.

Solutions

1. Read the rich panel printed just above the exception — it enumerates every invalid metric/label combination with the valid alternatives
2. Fix each entry so metric names come from DEFINED_PROMETHEUS_METRICS and labels come from that metric's allowed set
3. Register custom metadata labels via litellm.custom_prometheus_metadata_labels (and custom tags) before referencing them
4. Add a CI/deploy step that constructs the prometheus config to catch breakage before rollout

Example fix

# before (config)
litellm_settings:
  prometheus:
    labels:
      litellm_proxy_total_requests: [end_user, requested_model]  # wrong metric/labels

# after (config)
litellm_settings:
  prometheus:
    labels:
      litellm_proxy_total_requests_metric: [end_user, requested_model, requested_model_group]

# Fail fast in CI/deploy before the proxy boots with a bad config
from litellm.integrations.prometheus import PrometheusCallback
try:
    PrometheusCallback()._get_label_filters()
except ValueError as e:
    print(e)
    raise SystemExit('prometheus labels config invalid; fix before deploy')

try:
    callback = PrometheusCallback()
except ValueError as e:
    logger.error('Prometheus config rejected: %s', e)
    raise SystemExit(1)  # do not serve with silently missing metrics

When it happens

Trigger: Configuring prometheus label filters (litellm_settings prometheus labels config / per-metric group syntax like 'metric: [labels]') with a misspelled metric key, a label not valid for that metric, malformed syntax that parses to something unexpected, or duplicate/conflicting group entries.

Common situations: Copying a labels config from an older litellm release whose metric or label names have since changed; YAML typos; using a custom label without registering it via litellm.custom_prometheus_metadata_labels; expecting end_user/tags on a metric that does not expose them.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• {label_error.message}
• Prometheus exclude configuration validation failed
• {error.message}
• bucket_name must be provided for GCS destination
• Custom code guardrail requires a guardrail_name

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/9445c03916d27770. Report an issue: GitHub.

Appendix: source

Thrown at litellm/integrations/prometheus.py:709

        parsed_configs: Final = []
        self.enabled_metrics = set()

        for group_config in config:
            if isinstance(group_config, dict):
                parsed_config = PrometheusMetricsConfig(**group_config)
            else:
                parsed_config = group_config

            parsed_configs.append(parsed_config)
            self.enabled_metrics.update(parsed_config.metrics)

        # Validate all configurations
        validation_results: Final = self._validate_all_configurations(parsed_configs)

        if validation_results.has_errors:
            self._pretty_print_validation_errors(validation_results)
            error_message = "Configuration validation failed:\n" + "\n".join(validation_results.all_error_messages)
            raise ValueError(error_message)

        # Build label filters from valid configurations
        label_filters: Final = self._build_label_filters(parsed_configs)

        # Pretty print the processed configuration
        self._pretty_print_prometheus_config(label_filters)
        return label_filters

    def _parse_exclude_config(self) -> tuple[frozenset[str], frozenset[str]]:
        """Parse and validate the global ``exclude_metrics`` / ``exclude_labels`` settings."""
        from typing import get_args

        import litellm

        exclude_metrics: Final = frozenset(litellm.prometheus_exclude_metrics or ())
        exclude_labels: Final = frozenset(litellm.prometheus_exclude_labels or ())

        valid_metrics: Final = frozenset(get_args(DEFINED_PROMETHEUS_METRICS))

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