breaking: change `form.error` type from `any` to `unknown` by dummdidumm · Pull Request #16245 · sveltejs/kit

dummdidumm · 2026-07-06T13:06:23Z

The error property on RemoteResource (and by extension RemoteQuery, RemoteLiveQuery, and RemotePrerenderFunction results) is now typed as App.Error | undefined instead of any. All errors are now transformed through handleError before being surfaced on the .error property, matching how the server already serializes errors. This means .error is always an App.Error-shaped object ({ message: string, status: number, ... }) rather than potentially being an HttpError instance, a native Error, or a TypeError from network failures.

If you were using isHttpError(resource.error) to check the error shape, replace it with a simple truthiness check and access .status/.message directly:

<!-- before -->
{isHttpError(q.error)
    ? `${q.error.status}: ${q.error.body?.message}`
    : q.error
        ? JSON.stringify(q.error)
        : 'none'}

<!-- after -->
{q.error ? `${q.error.status}: ${q.error.message}` : 'none'}

Went through the any types on public.d.ts and these are the only changes that feel necessary. All the other are either ok (because really "any", or part of generics", or internal.

Closes #15674

Went through the `any` types on `public.d.ts` and these are the only changes that feel necessary. All the other are either ok (because really "any", or part of generics", or internal. Closes #15674

pkg-svelte-dev · 2026-07-06T13:06:26Z

Install the latest version of @sveltejs/kit from f3344e9:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/f3344e9db9b3f8e77a7bf0c8bf8b85313605e65e

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16245

changeset-bot · 2026-07-06T13:06:27Z

🦋 Changeset detected

Latest commit: f3344e9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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@sveltejs/kit	Major

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svelte-docs-bot · 2026-07-06T13:08:01Z

Preview: https://svelte-dev-git-preview-kit-16245-svelte.vercel.app/

Rich-Harris · 2026-07-06T17:24:29Z

 export type RemoteResource<T> = Promise<T> & {
 	/** The error in case the query fails. Most often this is a [`HttpError`](https://svelte.dev/docs/kit/@sveltejs-kit#HttpError) but it isn't guaranteed to be. */
-	get error(): any;
+	get error(): unknown;


as a follow-up (not for this PR) I think we could probably tighten this up — if it's not an App.Error then surely it can only be a NetworkError?

actually... maybe it should be part of this PR. feels like we could simplify usage a fair bit, including in the q.error test samples below. Do network errors go through handleError? If not, should they? If so, is there a sensible way to represent a network error as an App.Error?

good call - this makes more sense. The promise will stay as-is largely though, mainly so that our transformError will not transform it again.

…n the query rejection handler lets a superseded request clobber a newer successful result's state with a stale error. This commit fixes the issue reported at packages/kit/src/runtime/client/remote-functions/query/instance.svelte.js:130 ## Bug In `Query.#run()`'s `.catch` handler, the supersede guard was changed from synchronous to `async`: ```js .catch(async (e) => { const idx = this.#latest.indexOf(resolve); if (idx === -1) return; const error = await handle_error(e, { ... }); // <-- async gap untrack(() => { this.#latest.splice(0, idx).forEach((r) => r(undefined)); this.#error = error; this.#loading = false; }); reject(new HttpError(error.status, error)); }); ``` `#latest` is a shared array across concurrent `#run()` invocations. `refresh()` spawns new `#run()` calls that each push a resolver onto `#latest`, so multiple in-flight requests are expected and normal. ### Concrete trigger 1. Request **A** starts → `#latest = [resolveA]`. 2. `refresh()` starts request **B** → `#latest = [resolveA, resolveB]`. 3. A's underlying `#fn()` rejects → enters `.catch`, captures `idx = 0`, passes the `idx === -1` guard, then suspends on `await handle_error(...)`. 4. During that await, B's `#fn()` resolves (synchronous success path): it splices A out of `#latest`, sets `#ready = true`, `#raw = B's value`, `#error = undefined`. Now `#latest = [resolveB]`. 5. A resumes with the **stale** `idx = 0`. `splice(0, 0)` removes nothing, but it then sets `this.#error = error` (A's stale error) and `#loading = false`. Result: `#error` is set even though the latest refresh (B) succeeded, while `#raw` still holds B's value. The UI shows an error for a query that actually succeeded. The synchronous success path never had this problem because there is no await between its `indexOf` guard and the state mutation — the invariant "this request is still current" held atomically. The async rejection path broke that invariant. ## Fix Re-check `this.#latest.indexOf(resolve)` **after** the `await handle_error(...)` and bail out (`return`) if it's now `-1`. This restores the synchronous path's invariant: a request superseded during error handling correctly abandons its state mutation instead of clobbering a newer result. An early pre-await check is kept to avoid the (potentially costly) `handle_error` call for an already-superseded request. Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: Rich-Harris <hello@rich-harris.dev>

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to version-3, this PR will be updated. ⚠️

⚠️

⚠️ `version-3` is currently in **pre mode** so this branch has prereleases rather than normal releases. If you want to exit prereleases, run `changeset pre exit` on `version-3`. ⚠️

⚠️

⚠️ # Releases ## @sveltejs/kit@3.0.0-next.7 ### Major Changes - breaking: change `form.error` type from `any` to `App.Error | undefined` ([#16245](#16245)) - feat: allow adapters to provide additional Vite plugins ([#16206](#16206)) - breaking: move tracing out of the experimental namespace and remove the instrumentation flag ([#16260](#16260)) - breaking: remove `$app/stores` ([#15499](#15499)) - breaking: disallow `*.remote.ts/js` files unless `experimental.remoteFunctions` is enabled ([#16247](#16247)) - breaking: remove param files in folder in favor of `params.js/ts` file ([#16189](#16189)) ### Patch Changes - fix: defer `query.refresh()` in server commands until after the command body completes ([#16225](#16225)) - fix: resolve service worker and `tsconfig.json` based on Vite `root` setting ([#16229](#16229)) - fix: populate `$app/env/*` dynamic variables in contexts that don't run the dev server, such as `vite-node` ([#16223](#16223)) - fix: no longer throw "An impossible situation occurred" when a server-only module is imported by both server and client code ([#16257](#16257)) - fix: set `define` values on `globalThis` when running Vitest ([#16246](#16246)) - fix: serve `.ico` files with `image/x-icon` Content-Type ([#16234](#16234)) - fix: make `paths.origin` type looser ([#16215](#16215)) - fix: avoid client build warning about externalising `node:async_hooks` ([#16244](#16244)) - fix: allow reserved words (e.g. `delete`, `class`) as remote function export names ([#16264](#16264)) ## @sveltejs/adapter-netlify@7.0.0-next.2 ### Patch Changes - fix: ensure types for `platform.context` work ([#16255](#16255)) - Updated dependencies [[`ba78a0b`](ba78a0b), [`a248c9b`](a248c9b), [`7596981`](7596981), [`be72ed9`](be72ed9), [`a5bd7e2`](a5bd7e2), [`dec671f`](dec671f), [`82f3867`](82f3867), [`97eb324`](97eb324), [`e2a9ac0`](e2a9ac0), [`309bfb4`](309bfb4), [`522a86b`](522a86b), [`0ff547f`](0ff547f), [`3d4ff91`](3d4ff91), [`c925f2a`](c925f2a), [`7daf445`](7daf445)]: - @sveltejs/kit@3.0.0-next.7 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

breaking: change form.error type from any to unknown

d8fa956

Went through the `any` types on `public.d.ts` and these are the only changes that feel necessary. All the other are either ok (because really "any", or part of generics", or internal. Closes #15674

teemingc linked an issue Jul 6, 2026 that may be closed by this pull request

Review any types in public.d.ts #15674

Closed

teemingc added the types / typescript label Jul 6, 2026

fix lint

150fcd7

teemingc approved these changes Jul 6, 2026

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Rich-Harris reviewed Jul 6, 2026

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ensure it's always App.Error

789f2ce

vercel Bot reviewed Jul 7, 2026

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Comment thread packages/kit/src/runtime/client/remote-functions/query/instance.svelte.js

Rich-Harris approved these changes Jul 7, 2026

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Rich-Harris merged commit dec671f into version-3 Jul 7, 2026
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Rich-Harris deleted the any-types-check branch July 7, 2026 19:36

github-actions Bot mentioned this pull request Jul 7, 2026

Version Packages (next) #16212

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teemingc mentioned this pull request Jul 7, 2026

Review any types in public.d.ts #15674

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manuel3108 mentioned this pull request Aug 7, 2026

sv migrate sveltejs/cli#1124

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breaking: change `form.error` type from `any` to `unknown` - #16245

breaking: change `form.error` type from `any` to `unknown`#16245
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