generateContent() produces empty text output

[anishadoni]

Description of the bug:

when using generateContent, the value of output.candidates[0].content.parts[0].text is sometimes empty. See

Actual vs expected behavior:

async function expected() {
    const genAI = new GoogleGenerativeAI(process.env.GEMINI);
    const MODEL = "gemini-2.0-flash-001";
    const { response: output } = await genAI.getGenerativeModel({
        model: MODEL,
        systemInstruction: "you are a helpful assistant.",
        generationConfig: {
            maxOutputTokens: 1000,
            temperature: 0,
        }
    }).generateContent("what is the capital of france?");
    console.log(output.candidates[0].content.parts[0].text); // expected The capital of France is Paris.
}

async function actual() {
    const genAI = new GoogleGenerativeAI(process.env.GEMINI);
    const MODEL = "gemini-2.0-flash-001";
    const { response: output } = await genAI.getGenerativeModel({
        model: MODEL,
        systemInstruction: "you are a helpful assistant.",
        generationConfig: {
            maxOutputTokens: 1000,
            temperature: 0,
        }
    }).generateContent("what is the capital of france?");
    console.log(output.candidates[0].content.parts[0].text); // actual "".
}

Any other information you'd like to share?

I'm struggling to reproduce this error consistently. Sometimes it works on retries. There is no indication from logs that we hit an api rate limit

[davidwitten]

I'm also encountering this issue.

This happens on both Vertex and AI studio for me.

[IvanLH]

When the text is empty, does the response have the .promptFeedback field set? Or any other field?

[Kartikayy007]

Hey @IvanLH I’d like to contribute a fix for this issue. Is this still open for external contributions?

[H9660]

Hi @anishadoni I tried this out in my terminal and it dint showed my null output anywhere.

import {GoogleGenerativeAI} from '@google/generative-ai'
async function expected() {
  const genAI = new GoogleGenerativeAI('AIzaSyAzgvqgie9VoOuj0nLm8RmqN-LKmwIdruM');
  const MODEL = "gemini-2.0-flash-001";
  const { response: output } = await genAI.getGenerativeModel({
      model: MODEL,
      systemInstruction: "you are a helpful assistant.",
      generationConfig: {
          maxOutputTokens: 1000,
          temperature: 0,
      }
  }).generateContent("what is the capital of france?");
  console.log(output.candidates[0].content.parts[0].text==""?"NULL OUTPUT": output.candidates[0].content.parts[0].text); // expected The capital of France is Paris.
}
  
setInterval(expected, 6000)