parcel-bundler/parcel · error · Error

untarring failed: ${currentHeaderStart}@${filename}

Error message

untarring failed: ${currentHeaderStart}@${filename}

What it means

Thrown by `untar` when the parsed `filesize` field of a tar header is `NaN`, meaning the octal-ascii size field at the current header offset is empty or non-numeric. This indicates the gzip/tar payload is corrupt, truncated, or not actually an npm package tarball.

Source

Thrown at packages/dev/repl/SimplePackageInstaller/untar.js:60

      .map(c => String.fromCharCode(c))
      .join('');

    if (!filename) break;

    let filesize = parseInt(
      Array.from(
        bufferSliceNull(
          view,
          currentHeaderStart + TAR_HEADER_OFFSETS.filesize[0],
          TAR_HEADER_OFFSETS.filesize[1],
        ),
      )
        .map(c => String.fromCharCode(c))
        .join(''),
      8,
    );
    if (isNaN(filesize)) {
      throw new Error(`untarring failed: ${currentHeaderStart}@${filename}`);
    }

    let data = view.slice(
      currentHeaderStart + 512,
      currentHeaderStart + 512 + filesize,
    );
    files.set(filename.slice('package/'.length), data);

    currentHeaderStart = roundUpToMultipleOf512(
      currentHeaderStart + 512 + filesize,
    );
  }

  return files;
}

View on GitHub (pinned to 59484858a1)

Solutions

1. Re-fetch the tarball — truncation/corruption is usually transient.
2. Confirm the upstream fetch (error 104) actually succeeded and returned a gzip body.
3. Check the `currentHeaderStart@filename` in the message: offset 0 with a garbage filename means the whole payload is wrong; a later offset means mid-tar corruption.
4. If reproducible for one package, the registry tarball itself may be bad — try a different version.

function looksLikeGzip(buf) {
  return buf && buf.byteLength >= 2 && new Uint8Array(buf)[0] === 0x1f && new Uint8Array(buf)[1] === 0x8b;
}

try { files = untar(buffer); }
catch (e) {
  if (/untarring failed/.test(e.message)) { /* refetch tarball, retry once */ }
  else throw e;
}

When it happens

Trigger: The ArrayBuffer passed to `untar` is not a gzipped tar; the gzip was partially downloaded (truncation); decompression produced garbage; tar header offsets drifted due to an earlier misparse.

Common situations: Network truncation of a tarball fetch; CDN returned an HTML error page that was fed in as the tarball; version skew between pako inflate and the payload; concurrent modification of the buffer.

Related errors

• npmFetch failed: fetching ${tarball} - ${res.status}
• npmResolve failed: fetching ${name} - ${res.status}
• npmResolve failed: resolving ${name}@${version}
• ${name}@${version}: only npm semver dependencies are current
• Cannot require '${resolved}' in the browser

AI-assisted analysis of parcel-bundler/parcel@59484858a1 (2026-08-13). Data as JSON: /api/errors/3bcf06b56dd54d3d. Report an issue: GitHub.