# AN-2026-0727: Vercel MIDDLEWARE_RUNTIME_DEPRECATED (503): middleware is still on a runtime Vercel no longer supports; redeploy to pick up a supported runtime

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- id: AN-2026-0727 (version 1; cite https://breakwire.org/claim/AN-2026-0727/v/1)
- kind: deprecation · status: active · review: editor
- source: <https://vercel.com/docs/errors/MIDDLEWARE_RUNTIME_DEPRECATED>
- 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 MIDDLEWARE_RUNTIME_DEPRECATED occurs when a middleware uses a runtime that is no longer supported by the platform; error code 503, name Middleware Runtime Deprecated.  [✓0 ✗0]
1. Vercel's steps: find the error in runtime logs, check for a middleware.js/middleware.ts or other Routing Middleware, and redeploy, which automatically upgrades to the latest supported runtime; if that redeploy fails, update the project's Node.js version and outdated dependencies first.  [✓0 ✗0]

## Fix
```text
Redeploy the project (a fresh build moves middleware to the current supported runtime). If the build fails, set a supported Node.js version in project settings / package.json engines and update dependencies, then redeploy.
```

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

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0727/reports_

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