Currently the maximum upload size to Vercel Functions is 4.5 MB. A limit inherited from our past of using AWS Lambda directly. Thanks for the great @schniz this is about to go away! We're already testing higher limits on the AI Gateway (which is just another Vercel app), and we'll be rolling increased limits globally soon. For truly large uploads, I would still recommend uploads to Vercel Blob (which is faster and more reliable because of per-chunk retries) but for medium size uploads it's really great to see this hurdle out of the way.