fix(css): lightningcss minify failed when `build.target: 'es6'` by ilharp · Pull Request #21933 · vitejs/vite

ilharp · 2026-03-18T19:05:41Z

Repro

Running the following commands:

npx -y create-vite@latest -t vanilla --no-interactive
cd vite-project
npm i
echo 'export default { build: { target: "es6" } }' > vite.config.js
npm run build

will produce the following output:

> [email protected] build
> vite build

vite v8.0.0 building client environment for production...
✓ 9 modules transformed.
✗ Build failed in 76ms
error during build:
Build failed with 1 error:

[plugin vite:css-post]
Error: [lightningcss minify] Unsupported target "es6"
    at convertTargets (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21916:9)
    at minifyCSS (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21172:13)
    at async finalizeCss (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21016:36)
    at async Promise.all (index 1)
    at async Object.run (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:2437:22)
    at async PluginContextImpl.renderChunk (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:20555:19)
    at async plugin (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/bindingify-input-options-Cu7pt6SZ.mjs:1211:16)
    at async plugin.<computed> (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/bindingify-input-options-Cu7pt6SZ.mjs:1570:12)
    at aggregateBindingErrorsIntoJsError (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/error-CP8smW_P.mjs:48:18)
    at unwrapBindingResult (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/error-CP8smW_P.mjs:18:128)
    at #build (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/rolldown-build-4YnQkA76.mjs:3311:34)
    at async buildEnvironment (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:32794:64)
    at async Object.build (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:33216:19)
    at async Object.buildApp (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:33213:153)
    at async CAC.<anonymous> (file:///D:/a/vite-project/node_modules/vite/dist/node/cli.js:778:3) {
  errors: [Getter/Setter]
}

This only occurs when config.build.target is es6. It will not occur with es2015.

The reason js bundling works correctly is that oxc specifically supports the string es6 along with es2015:

https://github.com/oxc-project/oxc/blob/c481b2fc7423cbeaff7cfbded4e569618e3e4bda/crates/oxc_syntax/src/es_target.rs#L31

  fn from_str(s: &str) -> Result<Self, Self::Err> {
      match s.cow_to_ascii_lowercase().as_ref() {
          "es5" => Err(String::from("ES5 is not yet supported.")),
+         "es6" | "es2015" => Ok(Self::ES2015),
          "es2016" => Ok(Self::ES2016),

Using target: 'es6', cssMinify: 'lightningcss' in vite 7 also produces the same error. And since cssMinify: 'lightningcss' is the default behavior in vite 8, to reduce migration regressions, I suggest supporting es6 as an alias of es2015 for the convertTargets() method of plugin css.

This patch can also be safely backported to vite 7.

…s `es6` ## Repro Running the following commands: ```sh npx -y create-vite@latest -t vanilla --no-interactive cd vite-project npm i echo 'export default { build: { target: "es6" } }' > vite.config.js npm run build ``` will produce the following output: ```log > [email protected] build > vite build vite v8.0.0 building client environment for production... ✓ 9 modules transformed. ✗ Build failed in 76ms error during build: Build failed with 1 error: [plugin vite:css-post] Error: [lightningcss minify] Unsupported target "es6" at convertTargets (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21916:9) at minifyCSS (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21172:13) at async finalizeCss (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:21016:36) at async Promise.all (index 1) at async Object.run (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:2437:22) at async PluginContextImpl.renderChunk (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:20555:19) at async plugin (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/bindingify-input-options-Cu7pt6SZ.mjs:1211:16) at async plugin.<computed> (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/bindingify-input-options-Cu7pt6SZ.mjs:1570:12) at aggregateBindingErrorsIntoJsError (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/error-CP8smW_P.mjs:48:18) at unwrapBindingResult (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/error-CP8smW_P.mjs:18:128) at #build (file:///D:/a/vite-project/node_modules/rolldown/dist/shared/rolldown-build-4YnQkA76.mjs:3311:34) at async buildEnvironment (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:32794:64) at async Object.build (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:33216:19) at async Object.buildApp (file:///D:/a/vite-project/node_modules/vite/dist/node/chunks/node.js:33213:153) at async CAC.<anonymous> (file:///D:/a/vite-project/node_modules/vite/dist/node/cli.js:778:3) { errors: [Getter/Setter] } ``` This only occurs when `config.build.target` is `es6`. It will not occur with `es2015`. The reason js bundling works correctly is that oxc specifically supports the string `es6` along with `es2015`: https://github.com/oxc-project/oxc/blob/c481b2fc7423cbeaff7cfbded4e569618e3e4bda/crates/oxc_syntax/src/es_target.rs#L31 Using `target: 'es6', cssMinify: 'lightningcss'` in vite 7 also produces the same error. And since `cssMinify: 'lightningcss'` is the default behavior in vite 8, to reduce migration regressions, I suggest supporting `es6` as an alias of `es2015` for the `convertTargets()` method of plugin css. This patch can also be safely backported to vite 7.

bluwy

Makes sense to me 👍 I don't think we have to backport this yet since lightningcss support in vite 7 is experimental and they could migrate to the full es2015 string instead.

| datasource | package | from | to | | ---------- | ------- | ----- | ----- | | npm | vite | 7.3.1 | 8.0.3 | ## [v8.0.3](https://github.com/vitejs/vite/blob/HEAD/packages/vite/CHANGELOG.md#small-803-2026-03-26-small) ##### Features - update rolldown to 1.0.0-rc.12 ([#22024](vitejs/vite#22024)) ([84164ef](vitejs/vite@84164ef)) ##### Bug Fixes - **html:** cache unfiltered CSS list to prevent missing styles across entries ([#22017](vitejs/vite#22017)) ([5464190](vitejs/vite@5464190)) - **module-runner:** handle non-ascii characters in base64 sourcemaps ([#21985](vitejs/vite#21985)) ([77c95bf](vitejs/vite@77c95bf)) - **module-runner:** skip re-import if the runner is closed ([#22020](vitejs/vite#22020)) ([ee2c2cd](vitejs/vite@ee2c2cd)) - **optimizer:** scan is not resolving sub path import if used in a glob import ([#22018](vitejs/vite#22018)) ([ddfe20d](vitejs/vite@ddfe20d)) - **ssr:** ssrTransform incorrectly rewrites `meta` identifier inside `import.meta` when a binding named `meta` exists ([#22019](vitejs/vite#22019)) ([cff5f0c](vitejs/vite@cff5f0c)) ##### Miscellaneous Chores - **deps:** bump picomatch from 4.0.3 to 4.0.4 ([#22027](vitejs/vite#22027)) ([7e56003](vitejs/vite@7e56003)) ##### Tests - **html:** add tests for `getCssFilesForChunk` ([#22016](vitejs/vite#22016)) ([43fbbf9](vitejs/vite@43fbbf9)) ## [v8.0.2](https://github.com/vitejs/vite/blob/HEAD/packages/vite/CHANGELOG.md#small-802-2026-03-23-small) ##### Features - update rolldown to 1.0.0-rc.11 ([#21998](vitejs/vite#21998)) ([ff91c31](vitejs/vite@ff91c31)) ##### Bug Fixes - **deps:** update all non-major dependencies ([#21988](vitejs/vite#21988)) ([9b7d150](vitejs/vite@9b7d150)) ##### Miscellaneous Chores - **deps:** update dependency [@vitejs/devtools](https://github.com/vitejs/devtools) to ^0.1.5 ([#21992](vitejs/vite#21992)) ([b2dd65b](vitejs/vite@b2dd65b)) ## [v8.0.1](https://github.com/vitejs/vite/blob/HEAD/packages/vite/CHANGELOG.md#small-801-2026-03-19-small) ##### Features - update rolldown to 1.0.0-rc.10 ([#21932](vitejs/vite#21932)) ([b3c067d](vitejs/vite@b3c067d)) ##### Bug Fixes - **bundled-dev:** properly disable `inlineConst` optimization ([#21865](vitejs/vite#21865)) ([6d97142](vitejs/vite@6d97142)) - **css:** lightningcss minify failed when `build.target: 'es6'` ([#21933](vitejs/vite#21933)) ([5fcce46](vitejs/vite@5fcce46)) - **deps:** update all non-major dependencies ([#21878](vitejs/vite#21878)) ([6dbbd7f](vitejs/vite@6dbbd7f)) - **dev:** always use ESM Oxc runtime ([#21829](vitejs/vite#21829)) ([d323ed7](vitejs/vite@d323ed7)) - **dev:** handle concurrent restarts in `_createServer` ([#21810](vitejs/vite#21810)) ([40bc729](vitejs/vite@40bc729)) - handle `+` symbol in package subpath exports during dep optimization ([#21886](vitejs/vite#21886)) ([86db93d](vitejs/vite@86db93d)) - improve `no-cors` request block error ([#21902](vitejs/vite#21902)) ([5ba688b](vitejs/vite@5ba688b)) - use precise regexes for transform filter to avoid backtracking ([#21800](vitejs/vite#21800)) ([dbe41bd](vitejs/vite@dbe41bd)) - **worker:** `require(json)` result should not be wrapped ([#21847](vitejs/vite#21847)) ([0672fd2](vitejs/vite@0672fd2)) - **worker:** make worker output consistent with client and SSR ([#21871](vitejs/vite#21871)) ([69454d7](vitejs/vite@69454d7)) ##### Miscellaneous Chores - add changelog rearrange script ([#21835](vitejs/vite#21835)) ([efef073](vitejs/vite@efef073)) - **deps:** bump required `@vitejs/devtools` version to 0.1+ ([#21925](vitejs/vite#21925)) ([12932f5](vitejs/vite@12932f5)) - **deps:** update rolldown-related dependencies ([#21787](vitejs/vite#21787)) ([1af1d3a](vitejs/vite@1af1d3a)) - rearrange 8.0 changelog ([8e05b61](vitejs/vite@8e05b61)) - rearrange 8.0 changelog ([#21834](vitejs/vite#21834)) ([86edeee](vitejs/vite@86edeee)) ## [v8.0.0](https://github.com/vitejs/vite/blob/HEAD/packages/vite/CHANGELOG.md#800-2026-03-12) ##### Features - update rolldown to 1.0.0-rc.9 ([#21813](vitejs/vite#21813)) ([f05be0e](vitejs/vite@f05be0e)) - warn when `vite-tsconfig-paths` plugin is detected ([#21781](vitejs/vite#21781)) ([ada493e](vitejs/vite@ada493e)) ##### Bug Fixes - **deps:** update all non-major dependencies ([#21786](vitejs/vite#21786)) ([eaa4352](vitejs/vite@eaa4352))

bluwy approved these changes Mar 19, 2026

View reviewed changes

sapphi-red added feat: css p2-edge-case Bug, but has workaround or limited in scope (priority) labels Mar 19, 2026

sapphi-red changed the title ~~fix: css-post lightningcss minify failed when config.build.target is es6~~ fix(css): lightningcss minify failed when build.target: 'es6' Mar 19, 2026

sapphi-red merged commit 5fcce46 into vitejs:main Mar 19, 2026
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fix(css): lightningcss minify failed when `build.target: 'es6'`#21933

fix(css): lightningcss minify failed when `build.target: 'es6'`#21933
sapphi-red merged 1 commit intovitejs:mainfrom
ilharp-contrib:fix-lightningcss-minify-es6

ilharp commented Mar 18, 2026

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ilharp commented Mar 18, 2026

Repro

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