danny-avila/LibreChat · error · Error

Invalid endpoint for finetuned generation. Must be one of: $

Error message

Invalid endpoint for finetuned generation. Must be one of: ${validFinetunedEndpoints.join(', ')}

What it means

Third guard in generateFinetunedImage(): only two endpoints may be used for finetuned generation — '/v1/flux-pro-finetuned' and '/v1/flux-pro-1.1-ultra-finetuned'. If the caller-supplied `endpoint` is anything else, it is rejected before the HTTP call. The default (when endpoint is omitted) is '/v1/flux-pro-finetuned', which is valid, so this only fires when an explicit endpoint is supplied.

Source

Thrown at api/app/clients/tools/structured/FluxAPI.js:441

  }

  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,
      output_format: imageData.output_format || 'png',
      finetune_id: imageData.finetune_id,
      finetune_strength: imageData.finetune_strength || 1.0,
      guidance: imageData.guidance || 2.5,
    };

    // Add optional parameters if provided
    if (imageData.width) {
      payload.width = imageData.width;
    }

View on GitHub (pinned to 5ff282f900)

Solutions

Omit `endpoint` to use the default '/v1/flux-pro-finetuned'.
Set endpoint to exactly '/v1/flux-pro-finetuned' or '/v1/flux-pro-1.1-ultra-finetuned' (no trailing slash, exact case).
If you genuinely need a new endpoint, add it to the validFinetunedEndpoints array in the source after confirming BFL/fal support it.
Log the received endpoint value before the call to catch trailing-whitespace or encoding issues.

Example fix

// before
await fluxTool.invoke({
  action: 'generate_finetuned',
  prompt: 'a koi',
  finetune_id: 'ft-1',
  endpoint: '/v1/flux-pro', // not allowed for finetuned
});

// after
await fluxTool.invoke({
  action: 'generate_finetuned',
  prompt: 'a koi',
  finetune_id: 'ft-1',
  // endpoint omitted -> defaults to /v1/flux-pro-finetuned
});

Defensive patterns

Strategy: validation

Validate before calling

const FINETUNED_ENDPOINTS = ['/v1/flux-pro-finetuned', '/v1/flux-pro-1.1-ultra-finetuned'];
function buildFluxFinetunedArgs(input) {
  const endpoint = input.endpoint || '/v1/flux-pro-finetuned';
  if (!FINETUNED_ENDPOINTS.includes(endpoint)) {
    throw new Error(`endpoint must be one of: ${FINETUNED_ENDPOINTS.join(', ')}`);
  }
  return { action: 'generate_finetuned', ...input, endpoint };
}

Type guard

function isValidFinetunedEndpoint(arg) {
  const ep = arg?.endpoint || '/v1/flux-pro-finetuned';
  return ['/v1/flux-pro-finetuned', '/v1/flux-pro-1.1-ultra-finetuned'].includes(ep);
}

Try / catch

try {
  await fluxTool.invoke(args);
} catch (e) {
  if (/Invalid endpoint for finetuned/.test(e.message)) return 'That endpoint does not support finetuned generation.';
  throw e;
}

Prevention

Omit `endpoint` for finetuned runs unless you specifically need the ultra variant.
Keep a single shared allowlist constant both in client validation and the tool source.
Normalize endpoint strings (trim, lowercase path) before comparison.

When it happens

Trigger: Calling generate_finetuned with `imageData.endpoint` set to a value not in the allowlist — e.g. '/v1/flux-pro', '/v1/flux-dev', '/v1/flux-pro-1.1', or a typo like '/v1/flux-pro-finetuned/' (trailing slash).

Common situations: Caller reused a payload from a normal generate run (which uses '/v1/flux-pro'); attempted to point finetuned generation at a newer endpoint before adding it to the allowlist; trailing-slash or case mismatch; stale docs listing an old endpoint name.

Related errors

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/652a50bccdd19df3. Report an issue: GitHub.