sveltejs/kit · error · Error

No `read` implementation was provided. Please ensure that yo

Error message

No `read` implementation was provided. Please ensure that your adapter is up to date and supports this feature

What it means

Runtime guard in the read() export of $app/server: the platform-specific read implementation was never installed. Adapters inject this implementation at startup; when it is missing (older adapter, missing/unconfigured platform, or an environment that doesn't provide filesystem access), calling read(asset) cannot work and this error explains the adapter is out of date or unsupported.

Source

Thrown at packages/kit/src/runtime/app/server/index.js:23

/**
 * Read the contents of an imported asset from the filesystem
 * @example
 * ```js
 * import { read } from '$app/server';
 * import somefile from './somefile.txt';
 *
 * const asset = read(somefile);
 * const text = await asset.text();
 * ```
 * @param {string} asset
 * @returns {Response}
 * @since 2.4.0
 */
export function read(asset) {
	__SVELTEKIT_TRACK__('$app/server:read');

	if (!read_implementation) {
		throw new Error(
			'No `read` implementation was provided. Please ensure that your adapter is up to date and supports this feature'
		);
	}

	// handle inline assets internally
	const match = /^data:([^;,]+)?(;base64)?,/.exec(asset);
	if (match) {
		const type = match[1] ?? 'application/octet-stream';
		const data = asset.slice(match[0].length);

		if (match[2] !== undefined) {
			const decoded = base64_decode(data);

			// @ts-ignore passing a Uint8Array to `new Response(...)` is fine
			return new Response(decoded, {
				headers: {
					'Content-Length': decoded.byteLength.toString(),
					'Content-Type': type

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Upgrade your @sveltejs/adapter-* package to the latest version
2. Make sure the built server is started through the adapter's output (e.g. node build/index.js), not by importing the source directly
3. If using a custom adapter, provide the read implementation via the emitted platform hooks

When it happens

Trigger: Thrown at packages/kit/src/runtime/app/server/index.js:23 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/6c5bbcb4924bf89e. Report an issue: GitHub.