alibaba/page-agent · error · InvokeError

INVALID_SCHEMA

INVALID_SCHEMA

Error message

No choices in response

What it means

The response parsed as JSON but its shape doesn't match the OpenAI chat completion schema — data.choices is missing or empty. The library expects at least one choice to extract finish_reason and content/tool calls; the raw data is attached as details for inspection.

Source

Thrown at packages/llms/src/OpenAIClient.ts:144

			)
		}

		// 4. Parse and validate response
		let data: any
		try {
			data = await response.json()
		} catch (error) {
			if ((error as any)?.name === 'AbortError') throw error
			throw new InvokeError(
				InvokeErrorTypes.INVALID_RESPONSE,
				'Response body is not valid JSON',
				error
			)
		}

		const choice = data.choices?.[0]
		if (!choice) {
			throw new InvokeError(InvokeErrorTypes.INVALID_SCHEMA, 'No choices in response', data)
		}

		// Check finish_reason
		switch (choice.finish_reason) {
			case 'tool_calls':
			case 'function_call': // gemini
			case 'stop': // some models use this even with tool calls
				break
			case 'length':
				throw new InvokeError(
					InvokeErrorTypes.CONTEXT_LENGTH,
					'Response truncated: max tokens reached',
					undefined,
					data
				)
			case 'content_filter':
				throw new InvokeError(
					InvokeErrorTypes.CONTENT_FILTER,

View on GitHub (pinned to d02db1ee7c)

Solutions

1. Inspect the attached data payload — often it contains an error object explaining the real problem
2. If using a compatible gateway, verify it fully implements the choices[] contract, or test with the official OpenAI endpoint to isolate
3. Upgrade or configure the gateway/proxy that is mangling the response
4. Retry once — some providers intermittently return empty choices under load

// probe the endpoint once for schema compatibility
const probe = await fetch(url, { method: 'POST', headers, body: JSON.stringify({ model, messages: [{ role: 'user', content: 'ping' }] }) })
const json = await probe.json()
if (!Array.isArray(json.choices) || json.choices.length === 0) throw new Error('Endpoint does not return OpenAI-compatible choices[]')

const isNoChoicesError = (e: unknown): e is InvokeError =>
  e instanceof InvokeError && e.code === 'INVALID_SCHEMA' && /No choices/.test(e.message)

try {
  await client.invoke(req)
} catch (e) {
  if (isNoChoicesError(e)) {
    console.error('Raw provider payload:', e.details) // often contains a soft error
    throw e
  }
  throw e
}

When it happens

Trigger: invoke() against an endpoint that returns 200 with an OpenAI-incompatible body: an error object like {error: {...}} with 200 status, an empty choices array (some gateways do this on internal failure), or a provider whose /chat/completions shim is incomplete.

Common situations: Third-party 'OpenAI-compatible' gateways that don't fully implement the schema; provider returning a soft error in the body with HTTP 200; model returning empty choices under load; middleware stripping parts of the response.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• INVALID_RESPONSE
• CONFIG_ERROR
• NETWORK_ERROR
• AUTH_ERROR
• RATE_LIMIT

AI-assisted analysis of alibaba/page-agent@d02db1ee7c (2026-08-28). Data as JSON: /api/errors/bae4c11f2e84ced3. Report an issue: GitHub.