gohugoio/hugo · error

unsupported Dart Sass version detected, please upgrade to Da

Error message

unsupported Dart Sass version detected, please upgrade to Dart Sass 1.63.0 or later, see https://gohugo.io/functions/css/sass/#dart-sass

What it means

Raised when a Dart Sass binary is found but hugo.IsDartSassGeV2() reports it is older than 1.63.0 — the first release embedding the Embedded Sass protocol v2 into the main `sass` executable. Hugo (since v0.115+) talks that protocol, so older standalone `dart-sass-embedded` or pre-1.63 `sass` binaries cannot be used.

Source

Thrown at resources/resource_transformers/tocss/dartsass/client.go:56

// used as part of the cache key.
const transformationName = "tocss-dart"

// See https://github.com/sass/dart-sass-embedded/issues/24
// Note: This prefix must be all lower case.
const dartSassStdinPrefix = "hugostdin:"

func New(fs *filesystems.SourceFilesystem, rs *resources.Spec) (*Client, error) {
	if !Supports() {
		return &Client{}, nil
	}

	if hugo.DartSassBinaryName == "" {
		return nil, fmt.Errorf("no Dart Sass binary found in $PATH")
	}

	if !hugo.IsDartSassGeV2() {
		return nil, fmt.Errorf("unsupported Dart Sass version detected, please upgrade to Dart Sass 1.63.0 or later, see https://gohugo.io/functions/css/sass/#dart-sass")
	}

	if err := rs.ExecHelper.Sec().CheckAllowedExec(hugo.DartSassBinaryName); err != nil {
		return nil, err
	}

	var (
		transpiler *godartsass.Transpiler
		err        error
		infol      = rs.Logger.InfoCommand("Dart Sass")
		warnl      = rs.Logger.WarnCommand("Dart Sass")
	)

	transpiler, err = godartsass.Start(godartsass.Options{
		DartSassEmbeddedFilename: hugo.DartSassBinaryName,
		LogEventHandler: func(event godartsass.LogEvent) {
			message := strings.ReplaceAll(event.Message, dartSassStdinPrefix, "")
			switch event.Type {

View on GitHub ↗ (pinned to 8a468df065)

Solutions

1. Upgrade to Dart Sass 1.63.0+ (`brew upgrade sass/sass/sass`, `npm i -g sass@latest`, or a fresh release download) and remove any old `dart-sass-embedded` from PATH
2. Verify with `sass --embedded --version` that the new binary is the one Hugo finds first in $PATH
3. Update CI caches/images that pin an old dart-sass version; see https://gohugo.io/functions/css/sass/#dart-sass

Example fix

# before
sass --version   # 1.58.3
# after
npm i -g sass@latest
sass --version   # 1.77.x (>= 1.63.0)

sass --version | awk '{print $1}' # require >= 1.63.0 before building

When it happens

Trigger: Client construction for the dartsass transpiler where the discovered binary is `sass` < 1.63.0 or the legacy `dart-sass-embedded` executable; the version gate fails before any compilation starts.

Common situations: Upgrading Hugo while keeping an old dart-sass-embedded install (common after Hugo 0.115 removed embedded-binary support), pinned CI cache with a stale sass version, or distro packages shipping outdated dart-sass.

Related errors

• no Dart Sass binary found in $PATH
• deploy not supported in this version of Hugo; install a rele
• failed to resolve output path %q: %w
• module workspace %q does not exist. Check your module.worksp
• got unexpected EOF when executing %q. The user running hugo

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/1232d53cadbbadcd.json. Report an issue: GitHub ↗.