denoland/deno · error · RangeError

incomingMaxAge cannot be negative

Error message

incomingMaxAge cannot be negative

What it means

WebTransportDatagramDuplexStream.incomingMaxAge is a writable property (an 'unrestricted double?' in IDL) that caps how old received datagrams may be. Deno's setter in ext/web/webtransport.js rejects negative values and NaN with a RangeError. Zero is normalized to null (no age limit). The check happens in the setter, so even assigning from a computation throws synchronously.

Source

Thrown at ext/web/webtransport.js:803

      promise.resolve(undefined);
    }

    this.#sending = false;
  }

  get incomingMaxAge() {
    webidl.assertBranded(this, WebTransportDatagramDuplexStreamPrototype);
    return this.#incomingMaxAge;
  }

  set incomingMaxAge(value) {
    webidl.assertBranded(this, WebTransportDatagramDuplexStreamPrototype);
    value = webidl.converters["unrestricted double?"](
      value,
      "Failed to execute 'incomingMaxAge' on 'WebTransportDatagramDuplexStream'",
    );
    if (value < 0 || NumberIsNaN(value)) {
      throw new RangeError("incomingMaxAge cannot be negative");
    }
    if (value === 0) value = null;
    this.#incomingMaxAge = value;
  }

  get outgoingMaxAge() {
    webidl.assertBranded(this, WebTransportDatagramDuplexStreamPrototype);
    return this.#outgoingMaxAge;
  }

  set outgoingMaxAge(value) {
    webidl.assertBranded(this, WebTransportDatagramDuplexStreamPrototype);
    value = webidl.converters["unrestricted double?"](
      value,
      "Failed to execute 'outgoingMaxAge' on 'WebTransportDatagramDuplexStream'",
    );
    if (value < 0 || NumberIsNaN(value)) {
      throw new RangeError("outgoingMaxAge cannot be negative");

View on GitHub (pinned to 9ad36f7a2c)

Solutions

1. Pass a non-negative number of milliseconds, or null for no limit.
2. Map config sentinels explicitly: negative or missing means null, not -1.
3. Guard computed values: Number.isFinite(v) && v >= 0 before assigning.
4. Remember 0 is treated as null (disabled), not as 'expire immediately'.

Example fix

// before
duplex.incomingMaxAge = config.maxAgeMs ?? -1; // -1 sentinel throws

// after
duplex.incomingMaxAge =
  config.maxAgeMs != null && config.maxAgeMs > 0 ? config.maxAgeMs : null;

function toMaxAge(v) {
  return Number.isFinite(v) && v > 0 ? v : null;
}
duplex.incomingMaxAge = toMaxAge(config.maxAgeMs);

function isValidMaxAge(v) {
  return v == null || (typeof v === "number" && Number.isFinite(v) && v >= 0);
}

try { duplex.incomingMaxAge = v; } catch (e) { if (e instanceof RangeError) duplex.incomingMaxAge = null; else throw e; }

When it happens

Trigger: duplex.incomingMaxAge = -1 or a NaN from a bad calculation like undefined * 1000; reading a config value in milliseconds where a '-1 means unset' convention collides with this API; subtracting a larger baseline from a smaller timestamp.

Common situations: Translating config sentinels (-1 for 'default') from other APIs into WebTransport options; NaN leaking from optional fields ('maxAge: undefined' times a unit factor); unit conversions producing negative values when inputs are misordered.

Related errors

• outgoingMaxAge cannot be negative
• incomingHighWaterMark cannot be negative
• outgoingHighWaterMark cannot be negative
• BenchContext::start() has already been invoked
• ${prefix}Linter plugin name must only contain lowercase lett

AI-assisted analysis of denoland/deno@9ad36f7a2c (2026-08-20). Data as JSON: /api/errors/d67f2aeeacd2b5c2. Report an issue: GitHub.