HeyPuter/puter · error · HttpError

upstream_bad_request

upstream_bad_request

Error message

Gemini TTS did not return audio data

What it means

After Gemini returns from generateContent with responseModalities ['AUDIO'], GeminiTTSProvider extracts candidates[0].content.parts[0].inlineData.data. If that path is missing (no audio payload), it throws HTTP 400 (legacyCode upstream_bad_request) with fields.provider='gemini'. Commonly the model returned text or nothing instead of audio — e.g. the input tripped a safety filter, the model refused, or the response shape was unexpected.

Solutions

  1. Rephrase or sanitize the text to avoid content Gemini's safety filters reject, then retry.
  2. Confirm the model is a '-tts' model and the voice is a valid prebuilt name.
  3. Try the default voice/model to isolate whether the voice or model caused the empty audio.
  4. Inspect the full Gemini response server-side (add temporary logging of response.candidates) to see finishReason or safetyRatings.
  5. Retry once — transient empty responses can occur under load.
Defensive patterns

Strategy: fallback

Validate before calling

// Reduce the chance of an empty-audio response: sanitize/shorten text and
// stick to supported voice/model combos.
function sanitizeForGeminiTTS(text) {
  if (typeof text !== 'string' || !text.trim()) return null;
  // drop content likely to trip safety filters before sending
  return text.trim().slice(0, 5000);
}
const clean = sanitizeForGeminiTTS(userText);
if (clean) await driver.synthesize({ text: clean, provider: 'gemini', voice: 'Kore' });

Try / catch

try {
  await driver.synthesize({ text, provider: 'gemini', voice });
} catch (e) {
  if (e?.fields?.legacyCode === 'upstream_bad_request' && /did not return audio/.test(e.message)) {
    // likely a safety filter / model refusal — rephrase, switch voice/model, or fall back
    await driver.synthesize({ text: rephrased, provider: 'gemini', voice: 'Kore', model: 'gemini-2.5-flash-preview-tts' });
  } else throw e;
}

Prevention

When it happens

Trigger: Sending text Gemini declines to vocalize (disallowed content triggering safety filters), an empty/whitespace result after framing, a model/voice combo that returns text instead of audio, or an upstream response-format change. The provider does not retry; it surfaces the empty-audio result as a 400.

Common situations: Content that hits Gemini safety settings; very short or symbolic text the model doesn't treat as speech; API version drift where inlineData is nested differently; rate/quota responses that still return 200 but with no audio.

Related errors

AI-assisted analysis of HeyPuter/puter@908ec23eda (2026-08-12). Data as JSON: /api/errors/29c52bccf438cd0d. Report an issue: GitHub.

Appendix: source

Thrown at src/backend/drivers/ai-tts/providers/gemini/GeminiTTSProvider.ts:253

        // status and caused 4xx validation errors to page.
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        const response: any = await this.#client.models.generateContent({
            model,
            contents: [{ parts: [{ text: inputText }] }],
            config: {
                responseModalities: ['AUDIO'],
                speechConfig: {
                    voiceConfig: {
                        prebuiltVoiceConfig: { voiceName: voice },
                    },
                },
            },
        });

        // Extract audio data from response
        const part = response?.candidates?.[0]?.content?.parts?.[0];
        if (!part?.inlineData?.data) {
            throw new HttpError(400, 'Gemini TTS did not return audio data', {
                legacyCode: 'upstream_bad_request',
                fields: { provider: 'gemini' },
            });
        }

        const audioBase64: string = part.inlineData.data;
        const mimeType: string =
            part.inlineData.mimeType || 'audio/L16;rate=24000';

        // Convert base64 PCM to a WAV buffer for broad client compatibility
        const pcmBuffer = Buffer.from(audioBase64, 'base64');
        let outputBuffer: Buffer;
        let contentType: string;

        if (mimeType.startsWith('audio/L16') || mimeType === 'audio/pcm') {
            // Wrap raw PCM (16-bit LE, 24kHz, mono) in a WAV container
            outputBuffer = this.#wrapPcmInWav(pcmBuffer, 24000, 1, 16);
            contentType = 'audio/wav';

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