vitejs/vite · error · Error

Unsupported target "${e}"

Error message

Unsupported target "${e}"

What it means

Thrown by `convertTargets` (which maps esbuild-style targets to lightningcss targets) when an `es*` target's year is not in Vite's `esMap`. The map covers ES2015 through ES2025; any other ES year (e.g. `es2014`, `es2026`) cannot be converted and is rejected.

Source

Thrown at packages/vite/src/node/plugins/css.ts:3622

const versionRE = /\d/

const convertTargetsCache = new Map<
  string | string[],
  LightningCSSOptions['targets']
>()
export const convertTargets = (
  esbuildTarget: string | string[] | false,
): LightningCSSOptions['targets'] => {
  if (!esbuildTarget) return {}
  const cached = convertTargetsCache.get(esbuildTarget)
  if (cached) return cached
  const targets: LightningCSSOptions['targets'] = {}

  const entriesWithoutES = arraify(esbuildTarget).flatMap((e) => {
    const match = esRE.exec(e)
    if (!match) return e
    const year = match[1] === '6' ? 2015 : Number(match[1])
    if (!esMap[year]) throw new Error(`Unsupported target "${e}"`)
    return esMap[year]
  })

  for (const entry of entriesWithoutES) {
    if (entry === 'esnext') continue
    const index = entry.search(versionRE)
    if (index >= 0) {
      const browser = map[entry.slice(0, index)]
      if (browser === false) continue // No mapping available
      if (browser) {
        const [major, minor = 0] = entry
          .slice(index)
          .split('.')
          .map((v) => parseInt(v, 10))
        if (!isNaN(major) && !isNaN(minor)) {
          const version = (major << 16) | (minor << 8)
          if (!targets[browser] || version < targets[browser]!) {
            targets[browser] = version

View on GitHub (pinned to 89620f09af)

Solutions

1. Use a supported ES year: one of es2015–es2025 (es6 maps to 2015).
2. Upgrade Vite — newer ES years are added as lightningcss support lands.
3. Switch to explicit browser targets (e.g. `chrome100`) instead of ES versions if you only need broad support.
4. Set `build.target`/CSS target to `'esnext'` to skip conversion.

Example fix

// before
export default defineConfig({ build: { target: 'es2014' } });
// after
export default defineConfig({ build: { target: 'es2015' } });

const SUPPORTED_ES_YEARS = new Set([2015,2016,2017,2018,2019,2020,2021,2022,2023,2024,2025]);

function validateEsTarget(target) {
  for (const t of [].concat(target)) {
    const m = /^es(\d{4}|6)$/.exec(t);
    if (m) {
      const year = m[1] === '6' ? 2015 : Number(m[1]);
      if (!SUPPORTED_ES_YEARS.has(year)) throw new Error(`Unsupported ES target: ${t}`);
    }
  }
}
// validateEsTarget(config.build.target);

function isSupportedEsTarget(t) {
  const m = /^es(\d{4}|6)$/.exec(t);
  if (!m) return false;
  const year = m[1] === '6' ? 2015 : Number(m[1]);
  return new Set([2015,2016,2017,2018,2019,2020,2021,2022,2023,2024,2025]).has(year);
}

When it happens

Trigger: Setting `build.target` / `css.lightningcss.targets` to an `esYYYY` string whose year has no entry in `esMap` (line 3622). The regex `esRE` captures the year, and `esMap[year]` is undefined.

Common situations: Using a future ES version not yet supported by the installed Vite (e.g. `es2026` on an older Vite), a typo like `es2014` or `es5`, or copy-pasted browserlist targets that resolve to an unsupported ES year.

Related errors

• Unsupported target "${entry}"
• When "build.cssCodeSplit: false" is set, "rolldownOptions.in
• Failed to load PostCSS config: ${e}
• Unknown lang: ${lang}
• Unsupported dependency type: ${dep.type}

AI-assisted analysis of vitejs/vite@89620f09af (2026-08-03). Data as JSON: /data/errors/9b6a50f4c6b3edf8.json. Report an issue: GitHub.