vercel/ai · error · NoOutputGeneratedError

No output generated.

Error message

No output generated.

What it means

NoOutputGeneratedError thrown by the result object's `output` getter when generateText was called with an output specification (experimental_output) but the model finished without producing any usable output. The SDK guards the accessor so consumers get a clear error instead of undefined.

Source

Thrown at packages/ai/src/generate-text/generate-text.ts:1747

  get responseMessages() {
    return [
      ...this.initialResponseMessages,
      ...this.steps.flatMap(step => step.response.messages),
    ];
  }

  get request() {
    return this.finalStep.request;
  }

  get usage() {
    return this.totalUsage;
  }

  get output() {
    if (this._output == null) {
      throw new NoOutputGeneratedError();
    }

    return this._output;
  }
}

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Check `result.finishReason` before reading `result.output`; handle non-text finish reasons separately.
2. Ensure the prompt instructs the model to produce the final structured output rather than calling tools.
3. Wrap the `result.output` access in try/catch for NoOutputGeneratedError and fall back to raw text.
4. Check for content-filter/empty responses from the provider and retry with an adjusted prompt.
5. Update packages — some empty-output handling was fixed in newer releases.

Example fix

// before
const data = result.output;
// after
let data;
if (result.finishReason === 'stop') {
  data = result.output; // may still throw; see catch below
} else {
  data = fallbackForFinishReason(result.finishReason);
}
try { data = result.output; } catch (e) { if (NoOutputGeneratedError.isInstance(e)) data = null; else throw e; }

// guard before accessing output
function hasOutput(result) {
  return result.finishReason === 'stop' && typeof result.text === 'string' && result.text.length > 0;
}

import { NoOutputGeneratedError } from 'ai';
function isNoOutputGenerated(e): e is NoOutputGeneratedError {
  return NoOutputGeneratedError.isInstance(e);
}

let output;
try {
  output = result.output;
} catch (e) {
  if (NoOutputGeneratedError.isInstance(e)) {
    output = null; // handle empty generation, e.g. retry or fall back to result.text
  } else throw e;
}

When it happens

Trigger: Accessing `result.output` after generateText with `experimental_output`/output spec when the step produced no text content or the output was never assigned (e.g. finishReason was tool-calls, content-filter, or the model returned an empty response).

Common situations: Model refused or returned empty completion; finishReason is 'tool-calls' so no text output was generated; content filter blocked the response; prompt asked for tool use while an output schema was also expected.

Related errors

• No video generated.
• AI_EmptyResponseBodyError
• Amazon Bedrock returned no images. Status: ${response.status
• VERTEX_VIDEO_GENERATION_ERROR
• Tool "${toolName}" did not return structuredContent or parse

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/2d5c7e9a4fa41704. Report an issue: GitHub.