denoland/deno · error

empty response from

Error message

empty response from {url}

What it means

After the laufey archive download completes (including retries), the HTTP response body is empty: into_maybe_bytes() returned Ok(None), i.e. the server sent a 2xx response with zero bytes. The downloader treats an empty body as a hard error because it cannot even attempt the SHA-256 comparison on zero bytes.

Solutions

1. Re-run the command — transient empty responses usually resolve on a fresh request.
2. Verify the URL from the error with curl -IL to confirm the asset exists and has a non-zero Content-Length.
3. Disable/inspect HTTP(S)_PROXY and NO_PROXY settings if a corporate proxy is in play, or exempt the release host.
4. If it reproduces consistently, capture the exact URL and response headers and report it — a persistent empty 200 for a pinned asset is an upstream host problem.

Example fix

# before: opaque failure inside the tool
deno desktop
# error: empty response from https://.../laufey-v1.2.3-x86_64-unknown-linux-gnu.tar.gz

# after: triage the URL out-of-band, then retry
curl -IL 'https://.../laufey-v1.2.3-x86_64-unknown-linux-gnu.tar.gz'  # expect 200 + Content-Length > 0
deno desktop

# Probe the asset before launching the build; an empty/absent body shows up here
curl -fsSL -o /dev/null -w '%{http_code} %{size_download}\n' "$LAUFEY_ARCHIVE_URL"
# expect '200 <nonzero>'; anything else will fail inside deno too

Catch download errors, inspect the context chain for 'empty response from', and retry with capped exponential backoff (2-3 attempts); an empty body from a CDN is overwhelmingly transient, unlike a checksum mismatch which must never be retried blindly.

When it happens

Trigger: GET of the laufey release URL via download_with_progress_and_retries returns 204 No Content or a 200 with an empty body — e.g. a misbehaving mirror, a corporate proxy that swallows the body, a redirect chain ending in an empty object store response, or a transient CDN failure after the final retry succeeded at the header level.

Common situations: Corporate HTTP(S) proxies or SSL-inspecting middleboxes that return empty bodies; a truncated object-storage response on a flaky connection; the release asset was yanked and the host now serves an empty 200; rare transient CDN glitch.

Related errors

• checksum mismatch for
• Either `node` or `range` must be provided when reporting an…
• fetch failed
• TLS wrap attach (JS stream) failed
• ${bindingName} ${errCodeMessage} ${name}

AI-assisted analysis of denoland/deno@f7822238ca (2026-08-20). Data as JSON: /api/errors/367c21b4890e6abb. Report an issue: GitHub.

Appendix: source

Thrown at cli/tools/desktop.rs:1986

    let url = Url::parse(&laufey_release_url(&archive))?;
    let progress_bar = ProgressBar::new(ProgressBarStyle::DownloadBars);
    let progress = progress_bar.update(&archive);
    // Send a real User-Agent — some CDNs (incl. parts of GitHub
    // releases) start rate-limiting empty UAs aggressively.
    let mut headers = http::HeaderMap::new();
    if let Ok(ua) = http::HeaderValue::from_str(&format!(
      "deno-desktop/{} (+https://deno.com)",
      env!("CARGO_PKG_VERSION")
    )) {
      headers.insert(http::header::USER_AGENT, ua);
    }
    let response = client
      .download_with_progress_and_retries(url.clone(), &headers, &progress)
      .await
      .with_context(|| format!("failed to download {url}"))?;
    let data = response
      .into_maybe_bytes()?
      .ok_or_else(|| deno_core::anyhow::anyhow!("empty response from {url}"))?;

    let actual =
      faster_hex::hex_string(&sha2::Sha256::digest(&data)).to_lowercase();
    let expected_lc = expected.to_lowercase();
    if actual != expected_lc {
      // Include the URL in the bail: an attacker who poisoned a redirect
      // would otherwise be invisible in the failure log.
      bail!(
        "checksum mismatch for {archive} (downloaded from {url})\n  expected: {expected_lc}\n  actual:   {actual}"
      );
    }

    let parent = dir.parent().ok_or_else(|| {
      deno_core::anyhow::anyhow!(
        "LAUFEY cache dir has no parent: {}",
        dir.display()
      )
    })?;

View on GitHub (pinned to f7822238ca)