solid-query 6.0.0-rc.5: onCacheEvent throws NotReadyError during a Solid 2 (rc.14+) transition landing

Start with the reproduction test in the issue, run under both the prod and dev builds, to see the unhandled NotReadyError. The throw comes from the untracked read of defaultedOptions inside onCacheEvent in the solid-query useBaseQuery hook, so read that handler and the observer.options it could use instead. Done means the repro passes in both builds with no unhandled error and the third transition commits, and the existing solid-query tests still pass.

Describe the bug

With Solid 2 rc.14+ (solid-js / @solidjs/signals 2.0.0-rc.15), useBaseQuery's onCacheEvent can throw NotReadyError while a transition lands. The throw escapes unhandled, aborts the landing, and the next transition never commits.

The chain:

1. A transition lands, and an unmounting useQuery runs its onCleanup: observer.destroy() → QueryCache.notify.
2. The notify reaches a sibling useQuery on the same key that was created inside that (still held) transition.
3. Its onCacheEvent compares event.query.queryHash === untrack(defaultedOptions).queryHash. defaultedOptions is a memo born held, and since rc.14 an untracked read of such a node throws NotReadyError (Solid 2 diagnostic A19, exception 1).

In an app with @solidjs/router this looks like a navigation that never finishes.

Your minimal, reproducible example

Inline below (vitest + jsdom; no app code). jsdom is needed because isServer is typeof window === "undefined", and without it the cache subscription is never created.

Steps to reproduce

vitest.config.mjs:

import { defineConfig } from "vitest/config";
const dev = process.env.MODE === "dev";
const conditions = dev ? ["development", "browser"] : ["browser"];
export default defineConfig({
  test: {
    pool: "forks",
    environment: "jsdom",
    server: { deps: { inline: [/solid-js/, /@solidjs/, /@tanstack\/solid-query/] } },
  },
  resolve: { conditions },
  ssr: { resolve: { conditions, externalConditions: conditions } },
});

repro.test.mjs:

import { QueryClient, useQuery } from "@tanstack/solid-query";
import { createMemo, createRenderEffect, createRoot, createSignal, flush, onCleanup } from "solid-js";
import { expect, it } from "vitest";

const tick = () => new Promise((r) => setTimeout(r, 0));

it("query torn down on landing must not abort it for a sibling born in the transition", async () => {
  const gates = [];
  const releaseAll = async () => {
    for (let i = 0; i < 6; i++) {
      for (const open of gates.splice(0)) open();
      await tick();
      flush();
      await tick();
    }
  };
  const flight = (k) => (k > 0 ? new Promise((r) => gates.push(r)).then(() => k) : Promise.resolve(k));
  const client = new QueryClient({ defaultOptions: { queries: { retry: false, gcTime: Infinity } } });
  const [s, setS] = createSignal(0);
  const shown = [];
  const dispose = createRoot((done) => {
    const screen = createMemo(() => {
      const k = s();
      const q = useQuery(() => ({ queryKey: ["repro"], queryFn: async () => "answer" }), () => client);
      return () => (q.isSuccess ? k : -1);
    });
    const pending = createMemo(async () => flight(s()));
    createRenderEffect(
      () => [screen()(), pending()],
      ([k]) => { shown.push(k); },
    );
    return done;
  });
  flush();
  await releaseAll();
  setS(1); flush(); await tick();
  setS(2); flush(); await releaseAll();
  setS(3); flush(); await releaseAll();
  expect(s()).toBe(3);
  expect(shown.at(-1)).toBe(3);
  dispose();
  client.clear();
});

Run with MODE=prod NODE_ENV=production npx vitest run repro.test.mjs, or MODE=dev NODE_ENV=development for the dev build.

patches applied	prod build	dev build
none	assertion fails (s() stays 2), unhandled NotReadyError	same
adapter change below only	passes, no error	same
Solid fix from solidjs/solid#4089 only	assertion passes, NotReadyError still unhandled	same
both	passes, no error	same

We confirmed the source of the throw by temporarily wrapping untrack(defaultedOptions) in onCacheEvent with a try/catch, which caught NotReadyError on cache events during the landing.

Expected behavior

The test passes: onCacheEvent does not throw during a landing, and the third transition commits (s() === 3, last rendered value 3).

Possible fix

observer.options is what the committed render effect last passed to observer.setOptions, so it holds the hook's current hash in a plain object instead of the reactive graph:

-    if (event.query.queryHash === untrack(defaultedOptions).queryHash || event.query.queryHash === latestHash) {
+    if (event.query.queryHash === observer.options.queryHash || event.query.queryHash === latestHash) {

With this change the reproduction passes in both builds. We have not run the solid-query test suite against it.

How often does this bug happen?

Every time

Platform

• Node v25.8.2, macOS; vitest 4.1.11, jsdom 29.1.1. The navigation hang also shows up in Chrome.

Tanstack Query adapter

solid-query

TanStack Query version

@tanstack/solid-query 6.0.0-rc.5 (@tanstack/query-core 5.101.4)

Additional context

• solid-js 2.0.0-rc.15 / @solidjs/signals 2.0.0-rc.15. Not reproducible on rc.13, which has no throwing branch for untracked reads of held nodes.
• Related Solid issue on the same landing path: solidjs/solid#4089. Fixing either side alone does not cover the other: the Solid fix hides the stuck transition, but the NotReadyError from the adapter still escapes.
• Possibly related: #11903 (a different symptom of the same useBaseQuery relay under Solid 2).