danny-avila/LibreChat · error · Error

Empty file uploaded

Error message

Empty file uploaded

What it means

filterFile() throws this at process.js:1328 when multer populated req.file but file.size === 0. The guard exists because a zero-byte file would otherwise be saved, referenced by a file_id, and silently corrupt later processing (image resize, RAG ingest). It is an early, explicit failure for a degenerate multipart upload.

Source

Thrown at api/server/services/Files/process.js:1328

 * @param {number} [params.req.width]
 * @param {number} [params.req.height]
 * @param {number} [params.req.version]
 * @param {boolean} [params.image] - Whether the file expected is an image.
 * @param {boolean} [params.isAvatar] - Whether the file expected is a user or entity avatar.
 * @returns {void}
 *
 * @throws {Error} If a file exception is caught (invalid file size or type, lack of metadata).
 */
function filterFile({ req, image, isAvatar }) {
  const { file } = req;
  const { endpoint, endpointType, file_id, width, height } = req.body;

  if (!file_id && !isAvatar) {
    throw new Error('No file_id provided');
  }

  if (file.size === 0) {
    throw new Error('Empty file uploaded');
  }

  /* parse to validate api call, throws error on fail */
  if (!isAvatar) {
    isUUID.parse(file_id);
  }

  if (!endpoint && !isAvatar) {
    throw new Error('No endpoint provided');
  }

  const appConfig = req.config;
  const fileConfig = mergeFileConfig(appConfig.fileConfig);

  const endpointFileConfig = getEndpointFileConfig({
    endpoint,
    fileConfig,
    endpointType,

View on GitHub (pinned to 5ff282f900)

Solutions

1. On the client, reject files with size === 0 before constructing the FormData.
2. Inspect the raw multipart payload (Network tab) to confirm the file part carries bytes.
3. If using a streaming source, ensure the stream has ended and emitted data before appending.

Example fix

// before
form.append('file', new Blob([]), 'empty.txt');
// after
if (selectedFile.size === 0) { alert('File is empty'); return; }
form.append('file', selectedFile, selectedFile.name);

function isValidUploadFile(file) {
  return !!file && typeof file.size === 'number' && file.size > 0;
}

const isNonEmptyFile = (f) => !!f && f.size > 0;

When it happens

Trigger: A multipart upload whose file part has no content: the user picked a file then emptied it, a stream pipe closed before bytes flowed, or the client appended an empty Blob/File. Also seen when a proxy truncates the body.

Common situations: Drag-and-drop UI that lets a 0-byte file through. A frontend test that constructs FormData from an uninitialized Blob. Network middleware that strips the body under a size threshold.

Related errors

• No file_id provided
• No width provided
• No height provided
• Error uploading file: ${result.message}
• Unexpected batch upload response: ${JSON.stringify(result).s

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/a9dedf61cde19736. Report an issue: GitHub.