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.

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: signals rc.14+: a write from onCleanup during land() resurrects the landed transaction, and later transitions never commit 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: solid-query: EFFECT_RELAY_TEAR on Solid 2 when a query key changes — useBaseQuery relays the result through a version signal written from a render effect #11903 (a different symptom of the same useBaseQuery relay under Solid 2).