sveltejs/kit · warning

The `${keypath}` option is deprecated, and will be removed i

Error message

The `${keypath}` option is deprecated, and will be removed in a future version

What it means

SvelteKit's config validator wraps deprecated option validators via `deprecate` in options.js and warns when a deprecated config option is set. It is a non-fatal console warning emitted during `vite dev`/`build` config validation. The option still works today but will be removed in a future version.

Source

Thrown at packages/kit/src/core/config/options.js:333

	)
};

/** @type {Validator<ValidatedConfig>} */
export const validate_options = object(options, true);

/**
 * @param {Validator} fn
 * @param {(keypath: string) => string} get_message
 * @returns {Validator}
 */
function deprecate(
	fn,
	get_message = (keypath) =>
		`The \`${keypath}\` option is deprecated, and will be removed in a future version`
) {
	return (input, keypath) => {
		if (input !== undefined) {
			console.warn(styleText(['bold', 'yellow'], get_message(keypath)));
		}

		return fn(input, keypath);
	};
}

// Derive the names of SvelteKit's own config options from the schema, so they
// stay in sync automatically. These are used to separate Kit's options from
// `vite-plugin-svelte`'s options when config is passed via the Vite plugin.
const kit_defaults = validate_options({}, 'config');

/** The names of the options that live under the `kit` namespace */
export const kit_options = Object.keys(kit_defaults);

/** The names of the options that live under the `kit.experimental` namespace */
export const kit_experimental_options = Object.keys(kit_defaults.experimental);

/**

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Remove the deprecated option from svelte.config.js or rename it to the current option name shown in the SvelteKit docs/changelog
2. Regenerate config defaults with `npx sv create` or check `packages/kit/src/core/config/options.js` for what replaced the option
3. Silence temporarily by removing the key if you don't rely on its behavior

Example fix

// before
const config = { kit: { adapter: adapter(), someOldOption: true } };
// after
const config = { kit: { adapter: adapter() } }; // option removed/renamed per migration guide

// before dev/build: scan svelte.config.js against current option names
const deprecated = ['someOldOption'];
for (const key of deprecated) if (key in config.kit) console.warn(`remove kit.${key}`);

/** @returns {boolean} */ function hasDeprecatedOption(config, key) { return config?.kit && key in config.kit; }

When it happens

Trigger: Setting any option wrapped by `deprecate(...)` in svelte.config.js to a non-undefined value, e.g. a renamed or relocated option like an old `kit.*` or adapter option.

Common situations: Upgrading SvelteKit/adapter versions while keeping an old svelte.config.js; copying config snippets from outdated tutorials; typos that match a deprecated alias.

Related errors

• Reading `config.kit` inside adapters is deprecated — it shou
• ${keypath} cannot be empty
• Each member of ${keypath} must start with '.' — saw '${exten
• SvelteKit configuration (${keys}) no longer lives inside a `
• ${keypath} should be one of "${options}" or "${options[optio

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/c0d889fb54b1a6a2. Report an issue: GitHub.