sveltejs/kit · error · Error

Invalid export '${key}'${file ? ` in ${file}` : ''} (${hint}

Error message

Invalid export '${key}'${file ? ` in ${file}` : ''} (${hint})

What it means

SvelteKit validates that special route modules (+page, +layout, +page.server, +layout.server, +server) only export known keys; anything prefixed with '_' is allowed as a private helper. Exporting an unrecognized name causes the build/dev to fail with this error, including a hint that often points to the correct file type for that export.

Source

Thrown at packages/kit/src/utils/exports.js:21

 */
function validator(expected) {
	/**
	 * @param {any} module
	 * @param {string} [file]
	 */
	function validate(module, file) {
		if (!module) return;

		for (const key in module) {
			if (key[0] === '_' || expected.has(key)) continue; // key is valid in this module

			const values = [...expected.values()];

			const hint =
				hint_for_supported_files(key, file?.slice(file.lastIndexOf('.'))) ??
				`valid exports are ${values.join(', ')}, or anything with a '_' prefix`;

			throw new Error(`Invalid export '${key}'${file ? ` in ${file}` : ''} (${hint})`);
		}
	}

	return validate;
}

/**
 * @param {string} key
 * @param {string} ext
 * @returns {string | void}
 */
function hint_for_supported_files(key, ext = '.js') {
	const supported_files = [];

	if (valid_layout_exports.has(key)) {
		supported_files.push(`+layout${ext}`);
	}

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Move the export to the file type shown in the hint (e.g. `actions` belongs in +page.server.js)
2. Prefix genuinely private helpers with '_' (e.g. `export const _helper = ...`) or move them out of the route file
3. Fix typos in standard exports (`prerender`, `csr`, `ssr`, `trailingSlash`, `config`)
4. Check the Kit version's valid export list — APIs like `entries` only exist in newer versions

Example fix

// before: +page.js
export const actions = { default: () => ({}) };
// after: +page.server.js
export const actions = { default: async ({ request }) => ({ success: true }) };

const VALID = new Set(['load','prerender','csr','ssr','trailingSlash','config','actions','entries','GET','POST','PATCH','PUT','DELETE','OPTIONS','HEAD','fallback']);
export const checkExports = (mod) => Object.keys(mod).filter((k) => !k.startsWith('_') && !VALID.has(k));

const hasOnlyValidExports = (mod, valid) =>
  Object.keys(mod ?? {}).every((k) => k.startsWith('_') || valid.includes(k));

// This error is thrown at build/dev time; there is no runtime catch.
// Defend in CI by validating route modules before build:
try {
  await import('./src/routes/+page.js');
} catch (e) {
  if (e.message.startsWith('Invalid export')) process.exit(1);
}

When it happens

Trigger: Exporting an action/load-only name from the wrong module (e.g. `actions` in +layout.js, `GET` in +page.js); typos like `export const prerender = truee`; exporting helper functions without an '_' prefix; leftover exports from renamed Kit APIs.

Common situations: Moving code between +page.server.js and +page.js; copy-pasting route files; typos in config exports like `ssr`, `csr`, `trailingSlash`; exporting non-route utilities from route files.

Related errors

• ${keypath} cannot be empty
• Each member of ${keypath} must start with '.' — saw '${exten
• ${keypath} should be one of "${options}" or "${options[optio
• Invalid character escape sequence in ${id}
• Hexadecimal escape sequence in ${id} must be two characters

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/d44ebe169d75bced. Report an issue: GitHub.