danny-avila/LibreChat · error · Error

Missing required field: finetune_id for finetuned generation

Error message

Missing required field: finetune_id for finetuned generation. Please supply a finetune_id!

What it means

Second guard in generateFinetunedImage(): after prompt is present, a finetune_id is mandatory because the upstream /v1/flux-pro-finetuned endpoint rejects requests without it. The message is explicit about the missing field.

Source

Thrown at api/app/clients/tools/structured/FluxAPI.js:431

        const formattedDetails = JSON.stringify(finetuneDetails, null, 2);
        return [`Here are the available finetunes:\n${formattedDetails}`, null];
      }
      return JSON.stringify(finetuneDetails);
    } catch (error) {
      const details = this.getDetails(error?.response?.data || error.message);
      logger.error('[FluxAPI] Error while getting finetunes:', details);
      const errorMsg = `Failed to get finetunes: ${details}`;
      return this.isAgent ? this.returnValue([errorMsg, {}]) : new Error(errorMsg);
    }
  }

  async generateFinetunedImage(imageData, requestApiKey) {
    if (!imageData.prompt) {
      throw new Error('Missing required field: prompt');
    }

    if (!imageData.finetune_id) {
      throw new Error(
        'Missing required field: finetune_id for finetuned generation. Please supply a finetune_id!',
      );
    }

    // Validate endpoint is appropriate for finetuned generation
    const validFinetunedEndpoints = ['/v1/flux-pro-finetuned', '/v1/flux-pro-1.1-ultra-finetuned'];
    const endpoint = imageData.endpoint || '/v1/flux-pro-finetuned';

    if (!validFinetunedEndpoints.includes(endpoint)) {
      throw new Error(
        `Invalid endpoint for finetuned generation. Must be one of: ${validFinetunedEndpoints.join(', ')}`,
      );
    }

    let payload = {
      prompt: imageData.prompt,
      prompt_upsampling: imageData.prompt_upsampling || false,
      safety_tolerance: imageData.safety_tolerance || 6,

View on GitHub (pinned to 5ff282f900)

Solutions

1. Provide `finetune_id` (string) in the generate_finetuned payload.
2. If unknown, first call `action: 'list_finetunes'` to enumerate available finetune IDs.
3. Validate client-side that finetune_id is set before enabling the finetuned submit action.
4. Make the tool schema require finetune_id for the finetuned action so the model is forced to supply it.

Example fix

// before
await fluxTool.invoke({
  action: 'generate_finetuned',
  prompt: 'a koi',
});

// after
await fluxTool.invoke({
  action: 'generate_finetuned',
  prompt: 'a koi',
  finetune_id: 'flux-ft-20240101-abc',
});

function buildFluxFinetunedArgs(input) {
  if (typeof input.finetune_id !== 'string' || !input.finetune_id.trim()) {
    throw new Error('generate_finetuned requires a finetune_id.');
  }
  return { action: 'generate_finetuned', ...input };
}

function hasFinetuneId(arg) {
  return typeof arg?.finetune_id === 'string' && arg.finetune_id.trim().length > 0;
}

try {
  await fluxTool.invoke(args);
} catch (e) {
  if (/Missing required field: finetune_id/.test(e.message)) return 'Select a finetune first.';
  throw e;
}

When it happens

Trigger: Calling the Flux tool with `action: 'generate_finetuned'` and a valid `prompt`, but no `finetune_id` in imageData.

Common situations: The finetune ID was supposed to be selected from a list (list_finetunes) but the caller skipped that step; the ID lived in a variable that was undefined; copy/paste dropped the field; the model hallucinated a finetune call without the ID.

Related errors

• Invalid endpoint for finetuned generation. Must be one of: $
• Missing required field: prompt
• Missing required field: prompt
• Missing FLUX_API_KEY environment variable.
• Missing required field: prompt

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/03c52b745040918f. Report an issue: GitHub.