breaking: remove support for edge and node 20 runtimes by Rich-Harris · Pull Request #16520 · sveltejs/kit

Rich-Harris · 2026-07-25T17:57:03Z

The edge runtime has long since been deprecated (it confers no benefit; people should just use node on fluid compute, and SvelteKit 3 does not support Node 20

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pkg-svelte-dev · 2026-07-25T17:57:05Z

Install the latest version of @sveltejs/kit from fb2b32e:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/fb2b32ecc60ab4794702efea78debec474beef5c

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16520

changeset-bot · 2026-07-25T17:57:06Z

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Latest commit: fb2b32e

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@sveltejs/adapter-vercel	Major

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svelte-docs-bot · 2026-07-25T17:59:10Z

Preview: https://svelte-dev-git-preview-kit-16520-svelte.vercel.app/

@type

…th an empty config, so its `.vc-config.json` has no `runtime` field, which is required by Vercel's Build Output API. This commit fixes the issue reported at packages/adapter-vercel/index.js:355 ## Bug In `packages/adapter-vercel/index.js`, the server-side route-resolution function (used when `kit.router.resolution === 'server'`) was generated as: ```js await generate_serverless_function(`${builder.config.kit.appDir}/route`, {}, []); ``` `generate_serverless_function` calls `create_function_bundle(builder, ..., config)`, which writes `.vc-config.json` as: ```js { runtime: config.runtime, // <- undefined when config === {} ... } ``` Since the config is an empty object, `config.runtime` is `undefined`. `JSON.stringify` drops `undefined` properties, so the generated `.func/.vc-config.json` has **no `runtime` field**. ### Trigger / failure mode Any project deployed to Vercel with `kit.router.resolution: 'server'` produces a serverless `.func` for `${appDir}/route` without a `runtime`. Vercel's Build Output API requires a concrete runtime (e.g. `nodejs22.x`) for serverless functions, so the function is either rejected at deploy time or falls back to an unintended default. Every other serverless function in this adapter passes a resolved runtime: - Route groups: `const config = { ...defaults, ...route.config, runtime }` where `runtime = resolve_runtime(defaults.runtime, route.config.runtime)`. - Catchall: `{ ...defaults, runtime }` where `runtime = resolve_runtime(defaults.runtime)`. This function previously was an **edge** function that explicitly set `runtime: 'edge'`; after the migration to serverless the runtime was simply omitted. ## Fix Resolve the runtime and spread `defaults`, matching the catchall pattern: ```js const runtime = resolve_runtime(defaults.runtime); await generate_serverless_function( `${builder.config.kit.appDir}/route`, /** @type {any} */ ({ ...defaults, runtime }), [] ); ``` `resolve_runtime` is already imported from `./utils.js`, and it returns a valid `RuntimeKey` (e.g. `nodejs22.x`) or throws for unsupported runtimes — so the generated `.vc-config.json` now always contains a valid `runtime`. Also updated the stale "edge function" comment to "serverless function". Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: Rich-Harris <hello@rich-harris.dev>

Nic-Polumeyv · 2026-07-25T18:10:50Z

ambient.d.ts still imports RequestContext, which no longer exists, and since the serverless entry never passes platform, the App.Platform.context declaration can go with it. With generate_edge_function gone, rolldown_config, the build import, files/edge.js and the rolldown dependency are all unused. The adapter docs page also still lists edge and nodejs20.x as runtimes. Can PR the cleanup against this branch if that's easier.

Rich-Harris · 2026-07-25T18:57:22Z

good catches, thanks!

Nic-Polumeyv

A few leftovers. The troubleshooting section of the docs still describes edge functions: the fs paragraphs and the deployment protection section, which only applied to read fetching from the deployment on edge (the serverless entry uses createReadableStream). The config section in the page options docs also still opens with deploying parts of an app on the edge on Vercel as its example.

The runtime docs now list bun1.x, but RuntimeConfigKey only accepts experimental_bun1.x, so a typed config rejects the documented value. Vercel no longer labels the Bun runtime experimental, so this could become RuntimeKey | 'experimental_bun1.x', which the existing experimental_ strip already handles at runtime.

Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>

teemingc

Nice. In the future, we should bump vercel/nft and add a platform test for bun

Rich-Harris · 2026-07-26T00:09:43Z

the first of those is easy enough, at least #16522

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⚠️ # Releases ## @sveltejs/adapter-vercel@7.0.0-next.4 ### Major Changes - breaking: remove support for edge and Node 20 runtimes ([#16520](#16520)) ### Patch Changes - chore: bump `@vercel/nft` dependency ([#16522](#16522)) - Updated dependencies [[`6942ddb`](6942ddb), [`68137d4`](68137d4), [`15dc603`](15dc603), [`a4f1521`](a4f1521), [`629b45d`](629b45d), [`7a7833a`](7a7833a), [`e6591a0`](e6591a0), [`7a7833a`](7a7833a), [`b196a39`](b196a39), [`66bf343`](66bf343), [`4bde76b`](4bde76b), [`d9f05cb`](d9f05cb), [`40efca1`](40efca1), [`8ef5548`](8ef5548), [`9efb8f2`](9efb8f2), [`6a670dc`](6a670dc), [`3416dcc`](3416dcc), [`6850fa5`](6850fa5), [`e6591a0`](e6591a0), [`688bead`](688bead), [`b596610`](b596610), [`0f26c13`](0f26c13), [`110a3db`](110a3db), [`665d467`](665d467), [`9c8c60c`](9c8c60c)]: - @sveltejs/kit@3.0.0-next.13 ## @sveltejs/kit@3.0.0-next.13 ### Major Changes - breaking: replace the `noScroll` and `keepFocus` options of `goto` with a single `reset` option, and the `data-sveltekit-noscroll` and `data-sveltekit-keepfocus` attributes with `data-sveltekit-reset` ([#16558](#16558)) - breaking: deprecate `error(status, {...})` in favour of `error(status, message, {...})` ([#16540](#16540)) ### Minor Changes - feat: add shallow routing to `goto` and deprecate `pushState` and `replaceState` ([#16449](#16449)) - feat: preserve page state set through `goto(..., { state, persistState: true })` across reloads ([#16449](#16449)) ### Patch Changes - chore: deduplicate repeated CSP directive handling ([#16498](#16498)) - fix: avoid Vite dev server reload on initial page request ([#16553](#16553)) - fix: don't set a `null` `accept-language` header on internal `fetch` sub-requests when the incoming request has none ([#16527](#16527)) - fix: correctly detect prerendered paths in server `fetch` when `paths.base` is set ([#16525](#16525)) - fix: don't duplicate remote modules in the generated manifest ([#16532](#16532)) - fix: exclude inlined files from the page's `$app/manifest` immutable list ([#16531](#16531)) - perf: avoid quadratic remote form issue merging ([#16493](#16493)) - fix: don't attempt to serialize fetch responses when the request body is not a string or TypedArray ([#16501](#16501)) - fix: read the error status of `App.Error` in the `prerender` and `query.live` remote functions ([#16529](#16529)) - fix: propagate errors from prerendered remote responses instead of re-running the function ([#16535](#16535)) - fix: respect the status returned from `handleError` on the fallback error page served to error-page sub-requests ([#16528](#16528)) - fix: skip unnecessary `version.json` checks if `updated.current` is already `true` ([#16518](#16518)) - fix: allow generation of $app/tsconfig without TypeScript installed ([#16534](#16534)) - perf: use a `Set` to check element ids when validating fragment links during prerendering ([#16494](#16494)) - fix: only include `_app/immutable` files in `$app/manifest`'s `immutable` in the service worker ([#16531](#16531)) - fix: log errors caught by the Vite dev server handler ([#16550](#16550)) - fix: resolve `root` per instance of the SvelteKit Vite plugin ([#16513](#16513)) - fix: ignore path casing differences when warning about overridden Vite config on Windows ([#16545](#16545)) - fix: preserve the current URL search parameters when submitting a remote form without JavaScript ([#16373](#16373)) - fix: treeshake prerendered remote functions in the right chunks ([#16533](#16533)) - fix: error during development if the adapter does not support instrumentation and it exists ([#16548](#16548)) ## @sveltejs/adapter-netlify@7.0.0-next.5 ### Patch Changes - chore: replace @netlify/functions with @netlify/types for the Context type ([#16542](#16542)) - Updated dependencies [[`6942ddb`](6942ddb), [`68137d4`](68137d4), [`15dc603`](15dc603), [`a4f1521`](a4f1521), [`629b45d`](629b45d), [`7a7833a`](7a7833a), [`e6591a0`](e6591a0), [`7a7833a`](7a7833a), [`b196a39`](b196a39), [`66bf343`](66bf343), [`4bde76b`](4bde76b), [`d9f05cb`](d9f05cb), [`40efca1`](40efca1), [`8ef5548`](8ef5548), [`9efb8f2`](9efb8f2), [`6a670dc`](6a670dc), [`3416dcc`](3416dcc), [`6850fa5`](6850fa5), [`e6591a0`](e6591a0), [`688bead`](688bead), [`b596610`](b596610), [`0f26c13`](0f26c13), [`110a3db`](110a3db), [`665d467`](665d467), [`9c8c60c`](9c8c60c)]: - @sveltejs/kit@3.0.0-next.13 ## @sveltejs/adapter-static@4.0.0-next.2 ### Patch Changes - fix: match adapter-vercel's prerendered redirect handling when deploying to Vercel ([#16497](#16497)) - Updated dependencies [[`6942ddb`](6942ddb), [`68137d4`](68137d4), [`15dc603`](15dc603), [`a4f1521`](a4f1521), [`629b45d`](629b45d), [`7a7833a`](7a7833a), [`e6591a0`](e6591a0), [`7a7833a`](7a7833a), [`b196a39`](b196a39), [`66bf343`](66bf343), [`4bde76b`](4bde76b), [`d9f05cb`](d9f05cb), [`40efca1`](40efca1), [`8ef5548`](8ef5548), [`9efb8f2`](9efb8f2), [`6a670dc`](6a670dc), [`3416dcc`](3416dcc), [`6850fa5`](6850fa5), [`e6591a0`](e6591a0), [`688bead`](688bead), [`b596610`](b596610), [`0f26c13`](0f26c13), [`110a3db`](110a3db), [`665d467`](665d467), [`9c8c60c`](9c8c60c)]: - @sveltejs/kit@3.0.0-next.13 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

breaking: remove support for edge and node 20 runtimes

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Rich-Harris added the needs-platform-tests This PR needs to run platform tests in order to merge. label Jul 25, 2026

Rich-Harris commented Jul 25, 2026

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Comment thread packages/adapter-vercel/utils.js

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Rich-Harris added 4 commits July 25, 2026 14:49

auto-detect bun, update docs

1b51401

remove obsolete ambient.d.ts

ccb56dc

remove rolldown

d2c5a6d

remove edge.js

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Rich-Harris mentioned this pull request Jul 25, 2026

chore: bump adapter-vercel sveltejs/svelte.dev#2115

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Rich-Harris and others added 4 commits July 25, 2026 16:16

Update packages/adapter-vercel/utils.js

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Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>

error on edge runtime before attempting to resolve

117de03

remove experimental prefix

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remove outdated docs

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teemingc approved these changes Jul 25, 2026

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teemingc merged commit 9a95ecd into version-3 Jul 25, 2026
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teemingc deleted the remove-edge-runtime branch July 25, 2026 23:58

github-actions Bot mentioned this pull request Jul 25, 2026

Version Packages (next) #16509

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breaking: remove support for edge and node 20 runtimes - #16520

breaking: remove support for edge and node 20 runtimes#16520
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Rich-Harris commented Jul 25, 2026

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