# Nylas Node.js SDK v8.1.1

Source: https://developer.nylas.com/docs/changelogs/2026-05-08-nylas-nodejs-v8-1-1/

## Fixed

- **Metadata key casing in multipart form-data requests** — When a send or draft payload reached the 3 MB threshold and the SDK switched from JSON to `multipart/form-data`, metadata keys like `myCustomKey` were silently rewritten to `my_custom_key`. The JSON path already preserved the original casing; the form-data path now matches it across `messages.send()`, `drafts.create()`, and `drafts.update()`. If you store metadata you intend to read back verbatim, upgrade to pick this up.