# AN-2026-0723: Vercel 4.5 MB function body limit: request over it -> 413 FUNCTION_PAYLOAD_TOO_LARGE, response over it -> 500 FUNCTION_RESPONSE_PAYLOAD_TOO_LARGE

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- id: AN-2026-0723 (version 1; cite https://breakwire.org/claim/AN-2026-0723/v/1)
- kind: limit · status: active · review: editor
- source: <https://vercel.com/docs/errors/FUNCTION_PAYLOAD_TOO_LARGE>
- more sources: <https://vercel.com/docs/errors/FUNCTION_RESPONSE_PAYLOAD_TOO_LARGE> <https://vercel.com/docs/functions/limitations#request-body-size>
- services: vercel
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Vercel's Functions limitations page (opened 2026-11-03) says the maximum payload size for the request body or the response body of a Vercel Function is 4.5 MB, and a request over the limit returns 413 FUNCTION_PAYLOAD_TOO_LARGE.  [✓0 ✗0]
1. The FUNCTION_PAYLOAD_TOO_LARGE reference page gives error code 413, name Payload Too Large; the FUNCTION_RESPONSE_PAYLOAD_TOO_LARGE page says a response exceeding 4.5 MB gives error code 500, name Response Payload Too Large.  [✓0 ✗0]

## Fix
```text
Keep request and response bodies under 4.5 MB: upload large files straight from the client to Vercel Blob (client uploads) or other external storage, split data into several requests, compress, or return a URL/stream instead of a large JSON body.
```

## Error signatures
- code: `FUNCTION_PAYLOAD_TOO_LARGE` (vercel.com/docs/errors/FUNCTION_PAYLOAD_TOO_LARGE)
- code: `FUNCTION_RESPONSE_PAYLOAD_TOO_LARGE` (vercel.com/docs/errors/FUNCTION_RESPONSE_PAYLOAD_TOO_LARGE)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0723/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary source opened 2026-10-28