sveltejs/kit · error · Error

Unexpected option ${keypath}.${key} (did you mean config.${k

Error message

Unexpected option ${keypath}.${key} (did you mean config.${key}?)

What it means

When an unknown key is found inside `config.kit`, SvelteKit checks whether the same key exists at the top level of `config`. If it does, the error message hints that the option belongs in `config.<key>` rather than inside `kit`, and throws to stop the misplacement from being silently ignored.

Source

Thrown at packages/kit/src/core/config/options.js:393

		if ((input && typeof input !== 'object') || Array.isArray(input)) {
			throw new Error(`${keypath} should be an object`);
		}

		for (const key in input) {
			if (!(key in children)) {
				if (allow_unknown) {
					const value = input[key];
					if (value !== undefined) output[key] = value;
				} else {
					let message = `Unexpected option ${keypath}.${key}`;

					// special case
					if (keypath === 'config.kit' && key in kit_options) {
						message += ` (did you mean config.${key}?)`;
					}

					throw new Error(message);
				}
			}
		}

		for (const key in children) {
			const validator = children[key];
			output[key] = validator(input && input[key], `${keypath}.${key}`);
		}

		return output;
	};
}

/**
 * @param {any} fallback
 * @param {(value: any, keypath: string) => any} fn
 * @returns {Validator}
 */

View on GitHub (pinned to 03f1687fe6)

Solutions

Move the key out of `kit` and place it at the top level of the config object as the error suggests.
Consult the current SvelteKit docs to confirm where each option lives.
Remove the key entirely if it is no longer a valid option.

Example fix

// before
const config = {
  kit: { files: { lib: 'src/lib' } }
};
// after
const config = {
  files: { lib: 'src/lib' },
  kit: {}
};

Defensive patterns

Strategy: validation

Validate before calling

// fail fast on unknown kit keys before validating
const knownKitKeys = new Set(['adapter', 'paths', 'prerender', 'csp', 'alias', 'env', /* ... */]);
const unknown = Object.keys(cfg.kit ?? {}).filter((k) => !knownKitKeys.has(k));
if (unknown.length) console.warn('Unknown kit options (check top-level config):', unknown);

Type guard

function isMisplaced(key, cfg) { return key in (cfg.kit ?? {}) && key in cfg; }

Try / catch

try {
  build(config);
} catch (e) {
  if (String(e.message).includes('did you mean config.')) {
    const key = /config\.(\w+)\?/.exec(e.message)[1];
    config[key] = config.kit[key];
    delete config.kit[key];
  } else throw e;
}

Prevention

Check current docs for whether an option is root-level or under `kit`.
After pre-1.0 upgrades, diff your config against the official template.
Never guess option placement — search the SvelteKit docs first.

When it happens

Trigger: Putting a root-level option (such as one belonging next to `compilerOptions` or another top-level config field that exists in kit_options' unknown-key check) inside the `kit` object, e.g. kit: { files: ... } when `files` is a top-level key, then validating config.

Common situations: Merging configs from older project layouts, confusing root-level options with `kit` options after the pre-1.0 reorganization where many settings moved between the two.

Related errors

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/73132f0d11a3f14b. Report an issue: GitHub.