When you run dropbox-sdk-js on Node 20+, pin the SDK past v10.36.0; earlier versions assume node-fetch internals that native fetch lacks. If downloads fail with res.buffer is not a function, the SDK version is the problem, not your code.

Context: GitHub issue dropbox/dropbox-sdk-js #1130 (closed, resolved): Node 20's built-in fetch broke SDK calls that worked on Node 18; filesDownload failed with res.buffer is not a function. Fixed in #1167 by switching to the standard arrayBuffer() API, shipped in v10.36.0.