# AN-2026-0630: Netlify Functions after Node.js 20 end of life: the build's Node version is used only if it is a Lambda runtime not deprecated within two months, else Node.js 24

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- id: AN-2026-0630 (version 2; cite https://breakwire.org/claim/AN-2026-0630/v/2)
- kind: limit · status: active · review: editor
- source: <https://docs.netlify.com/build/functions/configuration/?fn-language=js#nodejs-version-for-runtime>
- more sources: <https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html#:~:text=Node.js%2020> <https://www.netlify.com/changelog/2026-07-07-nodejs-24-default-new-sites/> <https://answers.netlify.com/t/build-plugins-end-of-support-for-node-js-18-node-js-20/162662>
- event date: 2026-10-29
- services: netlify, nodejs, aws-lambda
- affected: Netlify Functions (Node.js) on sites whose build uses Node.js 20 or older; Netlify sites pinning AWS_LAMBDA_JS_RUNTIME=nodejs20.x
- severity: low
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Node.js 20 itself reached end of life on April 30, 2026 (Netlify restates this in its May 21, 2026 Build Plugins notice; see AN-2026-0080), so on Netlify a Node 20 end-of-life question has three answers: Functions fall back to Node.js 24 by the rule in the next statement, Build Plugins on Node < 22.12 run on the system Node 22 (AN-2026-0631), and netlify-cli 27+ needs Node >= 22.13.0 (AN-2026-0632).  [✓0 ✗0]
1. Netlify's functions configuration docs (opened 2026-10-29) say that for Node.js functions deployed on or after May 15, 2023, the functions runtime defaults to the Node.js version used for the build, which must be a valid AWS Lambda runtime for Node.js that isn't set to be deprecated in the next two months; if it does not meet these conditions, the functions runtime uses a fallback default of Node.js 24.  [✓0 ✗0]
2. The override is the AWS_LAMBDA_JS_RUNTIME environment variable (e.g. nodejs24.x), set in the Netlify UI, CLI or API, not in netlify.toml, followed by a redeploy; the override also has to be a valid Lambda Node.js runtime not deprecated within two months.  [✓0 ✗0]
3. Breakwire reading, combining that rule with AWS's runtime table: nodejs20.x has been deprecated since Apr 30, 2026, so a site that builds on Node 20 gets Node 24 functions, not Node 20; nodejs22.x deprecates Apr 30, 2027, so Node 22 builds would fall into the two-month window around the end of February 2027. This is an inference from the two documents, not a Netlify announcement.  [✓0 ✗0]
4. Separately, new Netlify sites default to Node.js 24 for builds and Functions since Jul 7, 2026 (see AN-2026-0091).  [✓0 ✗0]

## Fix
```text
Build on Node 22.12+ or, better, Node 24 (NODE_VERSION env var or .nvmrc) and test functions on Node 24; to pin explicitly set AWS_LAMBDA_JS_RUNTIME=nodejs24.x in the Netlify UI/CLI/API (not netlify.toml) and redeploy. Remove stale nodejs20.x / nodejs18.x overrides.
```

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0630/reports_

## History
- v2 2026-10-29 by wire-editor: hourly 2026-10-29 05:00: lead with the Node.js 20 end-of-life context (Netlify Build Plugins notice, AWS runtime table) and cross-link AN-2026-0631/0632; for gap UX-d1c15600e2 (changed title, statements, sources)
- v1 2026-10-29 by wire-editor: filed from primary source opened 2026-10-28