vitejs/vite · error · Error

Unsupported configLoader: ${configLoader}. Accepted values a

Error message

Unsupported configLoader: ${configLoader}. Accepted values are 'bundle', 'runner', and 'native'.

What it means

In loadConfigFromFile (config.ts:2376-2384), the configLoader parameter must be one of 'bundle', 'runner', or 'native'. Any other value throws. These select how the config file is loaded: bundled with esbuild, executed in a module runner, or natively imported.

Source

Thrown at packages/vite/src/node/config.ts:2381

export async function loadConfigFromFile(
  configEnv: ConfigEnv,
  configFile?: string,
  configRoot: string = process.cwd(),
  logLevel?: LogLevel,
  customLogger?: Logger,
  configLoader: 'bundle' | 'runner' | 'native' = 'bundle',
): Promise<{
  path: string
  config: UserConfig
  dependencies: string[]
} | null> {
  if (
    configLoader !== 'bundle' &&
    configLoader !== 'runner' &&
    configLoader !== 'native'
  ) {
    throw new Error(
      `Unsupported configLoader: ${configLoader}. Accepted values are 'bundle', 'runner', and 'native'.`,
    )
  }

  const start = performance.now()
  const getTime = () => `${(performance.now() - start).toFixed(2)}ms`

  let resolvedPath: string | undefined

  if (configFile) {
    // explicit config path is always resolved from cwd
    resolvedPath = path.resolve(configFile)
  } else {
    // implicit config file loaded from inline root (if present)
    // otherwise from cwd
    for (const filename of DEFAULT_CONFIG_FILES) {
      const filePath = path.resolve(configRoot, filename)
      if (!fs.existsSync(filePath)) continue

View on GitHub (pinned to 89620f09af)

Solutions

1. Use one of the accepted values: 'bundle' (default), 'runner', or 'native'.
2. Check for typos in the CLI flag or inline config option.
3. Leave configLoader unset to use the default 'bundle'.

Example fix

// before
createServer({ configLoader: 'esm' })
// after
createServer({ configLoader: 'bundle' })

const VALID_LOADERS = ['bundle', 'runner', 'native'] as const
if (!VALID_LOADERS.includes(configLoader as any)) {
  throw new Error(`Unsupported configLoader: ${configLoader}`)
}

function isConfigLoader(value: unknown): value is 'bundle' | 'runner' | 'native' {
  return value === 'bundle' || value === 'runner' || value === 'native'
}

When it happens

Trigger: Passing an unsupported configLoader string via the JS API (loadConfigFromFile / createServer({ configLoader })) or CLI --configLoader flag, e.g. 'esm', 'require', or a typo like 'bundel'.

Common situations: Migrating from an older Vite with different loader names, typos in config, or passing a custom loader name that isn't supported.

Related errors

• `renderLegacyChunks` and `renderModernChunks` cannot be both
• Invalid environment name "${name}". Environment names must o
• `input` cannot contain glob characters. They are reserved, s
• Required environments configuration were stripped out in the
• The value passed to "base" option was malformed. It should b

AI-assisted analysis of vitejs/vite@89620f09af (2026-08-03). Data as JSON: /data/errors/f8a122a985336c46.json. Report an issue: GitHub.