sveltejs/kit · error · Error

${keypath} must be a valid origin — only 'http' and 'https'

Error message

${keypath} must be a valid origin — only 'http' and 'https' protocols are supported, received '${url.protocol}'

What it means

Beyond parseability, the origin must use the `http:` or `https:` protocol. SvelteKit prerenders real HTTP pages, so schemes like `ftp:`, `file:`, `ws:` or custom app schemes are rejected, with the offending protocol included in the message.

Source

Thrown at packages/kit/src/core/config/options.js:231

			}

			return input;
		}),
		origin: validate(undefined, (input, keypath) => {
			assert_string(input, keypath);

			let url;

			try {
				url = new URL(input);
			} catch {
				throw new Error(
					`${keypath} must be a valid origin (e.g. 'https://my-site.com'). '${input}' could not be parsed as a URL`
				);
			}

			if (url.protocol !== 'http:' && url.protocol !== 'https:') {
				throw new Error(
					`${keypath} must be a valid origin — only 'http' and 'https' protocols are supported, received '${url.protocol}'`
				);
			}

			const origin = url.origin;

			if (input !== origin) {
				throw new Error(
					`${keypath} must be a valid origin — received '${input}' which contains a path, query, or hash. Use the bare origin '${origin}' instead`
				);
			}

			return origin;
		}),
		relative: boolean(true)
	}),

	preprocess: any(),

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Switch to `https://` (or `http://` for local testing): `https://my-site.com`
2. If you need local prerendering, use `http://localhost` or `http://sveltekit-prerender` as appropriate
3. Validate the protocol before assigning: `['http:', 'https:'].includes(new URL(v).protocol)`

Example fix

// before
prerender: { origin: 'file:///srv/site' }
// after
prerender: { origin: 'https://my-site.com' }

const origin = config.prerender?.origin;
if (origin !== undefined) {
  const protocol = new URL(origin).protocol;
  if (protocol !== 'http:' && protocol !== 'https:') {
    throw new Error(`prerender.origin must use http/https, got ${protocol}`);
  }
}

function isHttpOrigin(v) {
  try {
    const p = new URL(v).protocol;
    return p === 'http:' || p === 'https:';
  } catch {
    return false;
  }
}

try {
  assertHttpOrigin(config.prerender?.origin);
} catch (e) {
  if (String(e.message).includes("only 'http' and 'https' protocols")) {
    console.error('Replace the scheme with https:// (or http:// for local testing)');
  }
  throw e;
}

When it happens

Trigger: `prerender: { origin: 'ftp://my-site.com' }`, `origin: 'file:///path'`, or a custom scheme like `app://host` — anything where `url.protocol` is neither `http:` nor `https:`.

Common situations: Pasting a local file URL during local testing; using a websocket or app-deep-link scheme by mistake; npm package URLs (`package://`) pasted into config.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• ${keypath} must be a valid origin (e.g. 'https://my-site.com
• ${keypath} should be "fail", "warn", "ignore" or a custom fu
• ${keypath} option must be an absolute path, if specified. Se
• ${keypath} option must not end with '/'. See https://svelte.
• To suppress or handle this error, implement `${name}` in htt

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/f9125f7e36e0b5ef. Report an issue: GitHub.