denoland/deno · error · TypeError

BenchContext::start() has already been invoked

Error message

BenchContext::start() has already been invoked

What it means

The HTTP download of the laufey archive completed (after retries) but the body decoded to zero bytes, so there is nothing to SHA-256 verify and the fetch is treated as a failed download of that URL.

Source

Thrown at cli/js/40_bench.js:432

    allSlice,
    allLength,
  );
}

/** @param desc {BenchDescription} */
function createBenchContext(desc) {
  return {
    [SymbolToStringTag]: "BenchContext",
    name: desc.name,
    origin: desc.origin,
    start() {
      if (currentBenchId !== desc.id) {
        throw new TypeError(
          "The benchmark which this context belongs to is not being executed",
        );
      }
      if (currentBenchUserExplicitStart != null) {
        throw new TypeError(
          "BenchContext::start() has already been invoked",
        );
      }
      currentBenchUserExplicitStart = benchNow();
    },
    end() {
      const end = benchNow();
      if (currentBenchId !== desc.id) {
        throw new TypeError(
          "The benchmark which this context belongs to is not being executed",
        );
      }
      if (currentBenchUserExplicitEnd != null) {
        throw new TypeError("BenchContext::end() has already been invoked");
      }
      currentBenchUserExplicitEnd = end;
    },
  };

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Simply retry the command — empty 2xx bodies are usually transient
2. Bypass or fix the intercepting proxy for the laufey release host
3. Verify the URL with curl and confirm a non-empty payload and sane Content-Length
4. Clear the partial cache entry and re-run so a fresh download is attempted

const res = await fetch(url, { method: 'HEAD' });
const len = Number(res.headers.get('content-length'));
if (res.ok && len === 0) throw new Error('mirror/proxy returned empty body — switch network or mirror');

for (let i = 0; i < 3; i++) {
  try { return await download(url); }
  catch (e) {
    if (!/empty response/.test(String(e))) throw e;
    await sleep(1000 * (i + 1));
  }
}
throw new Error('empty response persisted after retries — check proxy/network');

When it happens

Trigger: A proxy or SSL-inspecting gateway returning a 2xx with an empty body; a transient origin/mirror fault; a redirect chain ending in an empty response.

Common situations: Corporate proxies and TLS-inspection appliances; captive-portal or degraded VPN networks; mirror outages.

Related errors

• The benchmark which this context belongs to is not being exe
• BenchContext::end() has already been invoked
• Bench attempted to exit with exit code: ${exitCode}
• Object is not a valid image or a path to an image. `Deno.jup
• Either `node` or `range` must be provided when reporting an

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/9f892ef2ec47cfef. Report an issue: GitHub.