FUNCTION_PAYLOAD_TOO_LARGE
what this Vercel error means
How it shows up
413: FUNCTION_PAYLOAD_TOO_LARGE
What it means
The data sent in the request body to a Vercel Function is larger than the allowed size, so the request is refused with 413. Vercel documents the limit as 4.5 MB.
The usual cause in an AI-built app
AI-generated upload features often send images or files to an API route as base64 inside JSON, which makes them even larger, so a photo from a phone can pass the limit quickly.
Check this first
In the browser Network tab, check the size of the failing request body and whether it is above 4.5 MB.