What causes "Remote file response too large: ${buffer.length} bytes" in danny-avila/LibreChat?

Raise the REMOTE_FILE_FETCH_MAX_BYTES limit if the file is legitimately large.

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

Error message

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

What it means

Thrown by saveURLToAzure (Azure/crud.js) when the fully buffered remote file exceeds getRemoteFileFetchMaxBytes(). node-fetch's `size` option is meant to abort mid-stream, but this is a defensive secondary check after response.buffer() resolves, catching cases where the Content-Length header was absent or lied.

Source

Thrown at api/server/services/Files/Azure/crud.js:84

  userId,
  URL,
  fileName,
  basePath = defaultBasePath,
  containerName,
}) {
  try {
    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`);
    }

    return await saveBufferToAzure({ userId, buffer, fileName, basePath, containerName });
  } catch (error) {
    logger.error('[saveURLToAzure] Error uploading file from URL:', error);
    throw error;
  }
}

/**
 * Retrieves a blob URL from Azure Blob Storage.
 *
 * @param {Object} params
 * @param {string} params.fileName - The file name.
 * @param {string} [params.basePath='images'] - The base folder used during upload.
 * @param {string} [params.userId] - If files are stored in a user-specific directory.
 * @param {string} [params.containerName] - The Azure Blob container name.
 * @returns {Promise<string>} The blob's URL.

View on GitHub (pinned to 5ff282f900)

Solutions

Raise the REMOTE_FILE_FETCH_MAX_BYTES limit if the file is legitimately large.
Reject oversized URLs upstream (HEAD request first, honor Content-Length) before downloading.
Confirm the fetch `size` option is being honored — upgrade node-fetch if the abort is silently ignored.
Inform the user the file exceeds the configured limit rather than retrying blindly.

Example fix

// before
const buffer = await response.buffer();
if (buffer.length > maxBytes) {
  throw new Error(`Remote file response too large: ${buffer.length} bytes`);
}

// after
const stated = Number(response.headers.get('content-length'));
if (stated && stated > maxBytes) {
  throw new Error(`Remote file too large: ${stated} bytes (limit ${maxBytes})`);
}
const buffer = await response.buffer();
if (buffer.length > maxBytes) {
  throw new Error(`Remote file response too large: ${buffer.length} bytes`);
}

Defensive patterns

Strategy: validation

Validate before calling

// Honor Content-Length before buffering
const stated = Number(response.headers.get('content-length'));
const maxBytes = getRemoteFileFetchMaxBytes();
if (stated && stated > maxBytes) {
  throw new Error(`Remote file too large (preflight): ${stated} > ${maxBytes}`);
}

Try / catch

try {
  await saveURLToAzure({ userId, URL, fileName });
} catch (err) {
  if (/Remote file response too large/.test(err.message)) {
    return res.status(413).json({ message: 'File exceeds the remote fetch size limit' });
  }
  throw err;
}

Prevention

Set REMOTE_FILE_FETCH_MAX_BYTES to a value that fits both your origin assets and your Azure limits.
HEAD-check Content-Length upstream to reject before downloading.
Reject oversized uploads at the client side before they reach the server.

When it happens

Trigger: A remote file with no (or understated) Content-Length header streams more bytes than the configured cap once fully buffered; the size abort did not fire because the header was missing.

Common situations: REMOTE_FILE_FETCH_MAX_BYTES env var set too low for legitimate use; user pointed at an unexpectedly large asset (e.g. a raw video instead of an image); chunked-transfer origin omitting Content-Length.

Related errors

AI-assisted analysis of danny-avila/LibreChat@5ff282f900 (2026-08-12). Data as JSON: /api/errors/080ecfe92b029062. Report an issue: GitHub.