What causes "Unknown target ${target} > ${targetLine} file:${file}" in oven-sh/bun?

Check the target name quoted in the error and correct it to bun, node, or deno

oven-sh/bun · error · TypeError

Unknown target ${target} > ${targetLine} file:${file}

Error message

Unknown target ${target}
> ${targetLine}
 file:${file}

What it means

Configuration error from the benchmark runner: a '// @runtime' directive parsed successfully, but one of its target names is not a key of the runner's `runtimes` map, which only contains bun, node, and deno. The error includes the offending target, the full directive line, and the file. Names are trimmed and lowercased before the lookup, so only genuinely unknown/misspelled names reach this throw.

Source

Thrown at bench/snippets/runner-entrypoint.js:47

    return;
  }

  const targetLine = sourceContents.slice(targetLineStart, targetLineEnd);
  const targets = targetLine
    .slice("// @runtime ".length)
    .split(/[,\s]+/gm)
    .map(a => a.trim().toLowerCase())
    .filter(Boolean)
    .sort();

  if (targets.length === 0) {
    throw new TypeError("No targets specified in " + JSON.stringify(file) + "\n> " + JSON.stringify(targetLine) + "\n");
  }

  var cmds = {};
  for (let target of targets) {
    if (!(target in runtimes)) {
      throw new TypeError(
        "Unknown target " + JSON.stringify(target) + "\n> " + targetLine + "\n file:" + JSON.stringify(file),
      );
    }

    switch (target) {
      case "bun": {
        if (!runtimes.bun) {
          continue;
        }

        cmds.bun = [runtimes.bun, "run", file];
        break;
      }

      case "node": {
        if (!runtimes.node) {
          continue;
        }

View on GitHub (pinned to 8c5296ac45)

Solutions

Check the target name quoted in the error and correct it to bun, node, or deno
If you need a new runtime, extend the `runtimes` map at the top of bench/snippets/runner-entrypoint.js and its switch statement
Re-run the runner after fixing the directive

Example fix

// before
// @runtime bun,nodej

// after
// @runtime bun,node

Defensive patterns

Strategy: validation

Validate before calling

const KNOWN_TARGETS = new Set(['bun', 'node', 'deno']);
const targets = runtimeLine.slice('// @runtime '.length).split(/[,\s]+/).map(s => s.trim().toLowerCase()).filter(Boolean);
const bad = targets.filter(t => !KNOWN_TARGETS.has(t));
if (bad.length) throw new TypeError('Unsupported runtime target(s): ' + bad.join(', '));

Type guard

function isKnownTarget(name) {
  return ['bun', 'node', 'deno'].includes(name.trim().toLowerCase());
}

Prevention

Restrict runtime lists to the names in the runtimes map at the top of runner-entrypoint.js: bun, node, deno
When adding a new runtime to the runner, update both the map and the switch before any snippet references it
Note that an installed-but-missing runtime (no node/deno binary) is skipped silently — only misspelled names throw, so check the quoted name carefully

When it happens

Trigger: A directive like '// @runtime bun,nodejs' (typo), '// @runtime v8' or any name outside {bun, node, deno}. Note this is about the name, not availability: a known-but-uninstalled runtime (node/deno not found) is skipped silently — only unknown names throw.

Common situations: Typos in the runtime list; targeting a runtime the runner has never heard of (workers, chrome, etc.); copy-pasting directives from a different harness.

Related errors

AI-assisted analysis of oven-sh/bun@8c5296ac45 (2026-08-16). Data as JSON: /api/errors/78b413b33617c299. Report an issue: GitHub.