denoland/deno · error

Invalid value for OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PRE

Error message

Invalid value for OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE: {}

What it means

OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE controls metrics temporality. The value is lowercased (casing is free) but NOT trimmed, and accepted names are only `cumulative` (default when unset), `delta` and `lowmemory`. Anything else fails telemetry init.

Source

Thrown at ext/telemetry/lib.rs:1311

        format!("{}-{}", rt_config.runtime_version, sdk_version),
      ),
    ])
    .build();

  // The OTLP endpoint is automatically picked up from the
  // `OTEL_EXPORTER_OTLP_ENDPOINT` environment variable. Additional headers can
  // be specified using `OTEL_EXPORTER_OTLP_HEADERS`.

  let temporality_preference = sys
    .env_var("OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE")
    .ok()
    .map(|s| s.to_lowercase());
  let temporality = match temporality_preference.as_deref() {
    None | Some("cumulative") => Temporality::Cumulative,
    Some("delta") => Temporality::Delta,
    Some("lowmemory") => Temporality::LowMemory,
    Some(other) => {
      return Err(deno_core::anyhow::anyhow!(
        "Invalid value for OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE: {}",
        other
      ));
    }
  };

  let (span_processor, meter_provider, log_processor) = if use_console_exporter
  {
    let span_exporter = console_exporter::ConsoleSpanExporter::new();
    let mut span_processor =
      BatchSpanProcessor::builder(span_exporter, OtelSharedRuntime).build();
    span_processor.set_resource(&resource);

    let metric_exporter =
      console_exporter::ConsoleMetricExporter::new(temporality);
    let metric_reader = DenoPeriodicReader::new(sys, metric_exporter);
    let meter_provider = SdkMeterProvider::builder()
      .with_reader(metric_reader)

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Use exactly `cumulative`, `delta` or `lowmemory` with no extra whitespace
2. Check for invisible characters: `printf '%s' "$OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE" | od -c`
3. Unset the variable to keep the default cumulative temporality

Example fix

# before — dash spelling, rejected
export OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE=low-memory

# after — exact token
export OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE=lowmemory

t="${OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE:-}"
case "${t,,}" in
  ""|cumulative|delta|lowmemory) ;;
  *) echo "invalid temporality preference: '$t'"; exit 1;;
esac
deno run --unstable-otel main.ts

const TEMPORALITIES = new Set(["cumulative", "delta", "lowmemory"]);
const isTemporality = (raw: string): boolean => {
  const v = raw.toLowerCase();
  return v === "" || TEMPORALITIES.has(v);
};

When it happens

Trigger: Setting the variable to `low-memory`, `low_memory`, `instantaneous`, or `cumulative ` (trailing space/newline) — separators and surrounding whitespace are not normalized.

Common situations: Spec names copied from blog posts that spell it low-memory; trailing whitespace from `export VAR=value ` in scripts; env files with CRLF line endings adding a carriage return.

Related errors

• vsock is not supported on this platform
• invalid vsock addr
• no private key found in OTEL_EXPORTER_OTLP_CLIENT_KEY file
• Env var OTEL_TRACES_SAMPLER specifies an unsupported sampler
• Env var OTEL_EXPORTER_OTLP_PROTOCOL specifies an unsupported

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/6958384bb9568b8d. Report an issue: GitHub.