danny-avila/LibreChat · error

Remote file response too large: ${buffer.length} bytes

Error message

Remote file response too large: ${buffer.length} bytes

What it means

Thrown by saveURLToFirebase after fetching a remote URL with node-fetch when the downloaded buffer exceeds the configured maximum (REMOTE_FILE_FETCH_MAX_BYTES, default 512 MB). The node-fetch `size` option should reject oversized responses mid-stream, but this check fires when the final buffer length exceeds the limit anyway — a defense-in-depth guard for when the remote server lies about Content-Length or omits it entirely.

Source

Thrown at api/server/services/Files/Firebase/crud.js:78

  const storage = getFirebaseStorage();
  if (!storage) {
    logger.error('Firebase is not initialized. Cannot save file to Firebase Storage.');
    return null;
  }

  const storageRef = ref(storage, `${basePath}/${userId.toString()}/${fileName}`);
  const maxBytes = getRemoteFileFetchMaxBytes();
  const response = await fetch(assertRemoteFileURL(URL), {
    timeout: getRemoteFileFetchTimeoutMs(),
    size: maxBytes,
  });
  if (!response.ok) {
    throw new Error(`Failed to fetch URL: ${response.status} ${response.statusText}`);
  }
  assertRemoteFileContentLength(response.headers, maxBytes);
  const buffer = await response.buffer();
  if (buffer.length > maxBytes) {
    throw new Error(`Remote file response too large: ${buffer.length} bytes`);
  }

  try {
    await uploadBytes(storageRef, buffer);
    return await getBufferMetadata(buffer);
  } catch (error) {
    logger.error('Error uploading file to Firebase Storage:', error.message);
    return null;
  }
}

/**
 * Retrieves the download URL for a specified file from Firebase Storage. This function initializes the
 * Firebase Storage and generates a reference to the file based on the provided basePath and file name. If
 * Firebase Storage is not initialized or if there is an error in fetching the URL, the error is logged
 * to the console.
 *
 * @param {Object} params - The parameters object.

View on GitHub (pinned to 5ff282f900)

Solutions

  1. Check whether the source URL legitimately needs to serve a large file; if so, raise REMOTE_FILE_FETCH_MAX_BYTES in your .env to accommodate it.
  2. Verify the remote URL is correct and not accidentally pointing to a download page, HTML wrapper, or redirect chain that inflates the payload.
  3. If the limit is intentional, validate file size before calling saveURLToFirebase by issuing a HEAD request and checking Content-Length against getRemoteFileFetchMaxBytes().
  4. Wrap the call in a try/catch and present a user-facing error indicating the file exceeds the maximum allowed size.

Example fix

// before
const result = await saveURLToFirebase({ userId, URL, fileName });

// after — pre-check with HEAD request
const maxBytes = getRemoteFileFetchMaxBytes();
const head = await fetch(assertRemoteFileURL(URL), { method: 'HEAD', timeout: 5000 });
const contentLength = parseInt(head.headers.get('content-length') ?? '0', 10);
if (contentLength > maxBytes) {
  throw new Error(`File exceeds maximum size of ${maxBytes} bytes`);
}
const result = await saveURLToFirebase({ userId, URL, fileName });
Defensive patterns

Strategy: validation

Validate before calling

const maxBytes = getRemoteFileFetchMaxBytes();
const head = await fetch(assertRemoteFileURL(URL), { method: 'HEAD', timeout: 5000 });
const contentLength = parseInt(head.headers.get('content-length') ?? '0', 10);
if (contentLength > maxBytes) {
  throw new Error(`File exceeds maximum size of ${maxBytes} bytes`);
}

Try / catch

try {
  const result = await saveURLToFirebase({ userId, URL, fileName });
  if (!result) {
    // handle null (init failure or upload error)
  }
} catch (error) {
  if (error.message.includes('too large')) {
    // surface user-friendly size error
  }
  throw error;
}

Prevention

When it happens

Trigger: Calling saveURLToFirebase({ URL }) where the remote host serves a file larger than REMOTE_FILE_FETCH_MAX_BYTES. This triggers when the response body is fully buffered and its length exceeds maxBytes, even though assertRemoteFileContentLength already inspected the header and node-fetch's `size` option was set.

Common situations: A user provides a URL to a very large image or document for upload. The remote CDN serves chunked encoding with no Content-Length, so the header-based pre-check passes but the actual body is oversized. Alternatively, REMOTE_FILE_FETCH_MAX_BYTES was lowered in .env to a restrictive value (e.g., 5 MB) and legitimate files now exceed it.

Related errors

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/9548499edd69f3bf. Report an issue: GitHub.