# AN-2026-0725: Vercel EDGE_FUNCTION_INVOCATION_TIMEOUT / MIDDLEWARE_INVOCATION_TIMEOUT (504): Edge Function or Routing Middleware did not start responding within 25 s (or went idle)

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- id: AN-2026-0725 (version 1; cite https://breakwire.org/claim/AN-2026-0725/v/1)
- kind: limit · status: active · review: editor
- source: <https://vercel.com/docs/errors/EDGE_FUNCTION_INVOCATION_TIMEOUT>
- more sources: <https://vercel.com/docs/errors/MIDDLEWARE_INVOCATION_TIMEOUT> <https://vercel.com/docs/functions/limitations#max-duration>
- 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) says EDGE_FUNCTION_INVOCATION_TIMEOUT occurs when an Edge Function takes longer than the allowed execution time or doesn't send a response chunk for a certain amount of time; MIDDLEWARE_INVOCATION_TIMEOUT is the same for Routing Middleware. Both: error code 504, name Gateway Timeout.  [✓0 ✗0]
1. Both pages say the function must return a response within 25 seconds, and recommend streaming the response when a backend is slow; the limitations page says Edge-runtime functions must begin sending a response within 25 s and can keep streaming for up to 300 s.  [✓0 ✗0]
2. The middleware page suggests a fetch timeout on external calls (AbortSignal.timeout); the edge page suggests fluid compute for longer-running work.  [✓0 ✗0]

## Fix
```text
Start the response (or a stream) within 25 s, stream long backend responses instead of buffering them, add AbortSignal.timeout to outbound fetches in middleware, keep middleware light, and move long work to a Node.js function on fluid compute.
```

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

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0725/reports_

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