# AN-2026-0722: Vercel NO_RESPONSE_FROM_FUNCTION (502 Bad Gateway): the invocation completed without returning a response (global uncaught exception / unhandled rejection, broken syntax in the deploy)

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- id: AN-2026-0722 (version 1; cite https://breakwire.org/claim/AN-2026-0722/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://vercel.com/docs/errors/NO_RESPONSE_FROM_FUNCTION>
- 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 error reference (opened 2026-11-03, last_updated 2026-02-09) says NO_RESPONSE_FROM_FUNCTION occurs when a function invocation completes without returning a response; error code 502, name Bad Gateway.  [✓0 ✗0]
1. Potential causes listed: a global uncaught exception, a global unhandled rejection, or a deployment that introduced incorrect syntax.  [✓0 ✗0]
2. Vercel recommends keeping the realtime request logs open while reproducing the error, and adding a Log Drain to persist function errors.  [✓0 ✗0]

## Fix
```text
Make sure every code path returns a response, catch module-level (global) exceptions and unhandled rejections, and reproduce with the realtime runtime logs open to see where it fails; roll back if the last deploy introduced a syntax error.
```

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

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0722/reports_

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