sveltejs/kit · error · Error

The SvelteKit options from the Vite config must be an…

Error message

The SvelteKit options from the Vite config must be an object. See https://svelte.dev/docs/kit/configuration

What it means

validate_config receives the `kit` (SvelteKit options) section exported from the Vite config. If that value is not an object (e.g. undefined, a string, or a function), validation cannot proceed, so it throws with a pointer to the configuration docs. This typically happens when svelte.config.js fails to export the config correctly or the Vite plugin receives malformed options.

Solutions

1. Ensure svelte.config.js exports the object as default: `export default { kit: {...} }` (or `module.exports = {...}`).
2. If using ESM/CJS interop in a custom loader, read `.default` from the imported module.
3. Check that the Vite plugin invocation receives the kit options object, not a string or function.

Example fix

// before: svelte.config.js missing export
const config = { kit: { adapter: adapter() } };
// after
const config = { kit: { adapter: adapter() } };
export default config;

const mod = await import('./svelte.config.js');
const config = mod.default ?? mod;
if (typeof config !== 'object' || config === null) {
  throw new Error('svelte.config.js must default-export an object');
}

/** @returns {config is Record<string, unknown>} */
function isKitConfig(value) {
  return typeof value === 'object' && value !== null;
}

try {
  const cfg = (await import('./svelte.config.js')).default;
} catch (e) {
  if (e.message.includes('must be an object')) {
    console.error('Check svelte.config.js: missing `export default config`?');
  }
  throw e;
}

When it happens

Trigger: validate_config is called (via extract_svelte_config / validate_paths) with a `config` argument whose typeof is not 'object' — commonly `undefined` because svelte.config.js has no default export, or the loaded module resolved to a non-object value.

Common situations: Forgetting `export default config` in svelte.config.js; a typo like `export defualt`; importing the config file from a CJS/ESM mismatch so the interop yields undefined; passing the config object inside a wrapper instead of directly.

Related errors

• should be an object
• Each member of must start with '.' — saw
• File extensions must be alphanumeric — saw
• Invalid isr.expiration value
• cannot be empty

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/d242b65fcff1e923. Report an issue: GitHub.

Appendix: source

Thrown at packages/kit/src/core/config/index.js:173

			config.files.hooks.server = path.resolve(cwd, config.files.hooks.server);
			config.files.hooks.universal = path.resolve(cwd, config.files.hooks.universal);
		} else if (key !== 'lib' /* TODO remove when we remove the `lib` option altogether */) {
			// @ts-expect-error
			config.files[key] = path.resolve(cwd, config.files[key]);
		}
	}

	return config;
}

/**
 * @param {Config} config
 * @returns {ValidatedConfig}
 */
export function validate_config(config) {
	try {
		if (typeof config !== 'object') {
			throw new Error(
				'The SvelteKit options from the Vite config must be an object. See https://svelte.dev/docs/kit/configuration'
			);
		}

		const validated = validate_options(config, 'config');
		const files = validated.files;

		files.hooks.client ??= path.join(files.src, 'hooks.client');
		files.hooks.server ??= path.join(files.src, 'hooks.server');
		files.hooks.universal ??= path.join(files.src, 'hooks');
		files.params ??= path.join(files.src, 'params');
		files.routes ??= path.join(files.src, 'routes');
		files.serviceWorker ??= path.join(files.src, 'service-worker');
		files.appTemplate ??= path.join(files.src, 'app.html');
		files.errorTemplate ??= path.join(files.src, 'error.html');

		if (validated.router.resolution === 'server') {
			if (validated.router.type === 'hash') {

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