fix(core): only attach .then and .catch onto a promise if it gets dehydrated by TkDodo · Pull Request #9847 · TanStack/query

TkDodo · 2025-11-05T13:30:12Z

🎯 Changes

✅ Checklist

I have followed the steps in the Contributing guide.
I have tested this code locally with pnpm run test:pr.

🚀 Release Impact

This change affects published code, and I have generated a changeset.
This change is docs/CI/dev-only (no release).

Summary by CodeRabbit

Bug Fixes
- Fixed unhandled promise rejections when dehydrating pending queries during server-side rendering.

…ydrated

changeset-bot · 2025-11-05T13:30:16Z

🦋 Changeset detected

Latest commit: 033c868

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

This PR includes changesets to release 19 packages

Name	Type
@tanstack/query-core	Patch
@tanstack/angular-query-experimental	Patch
@tanstack/query-async-storage-persister	Patch
@tanstack/query-broadcast-client-experimental	Patch
@tanstack/query-persist-client-core	Patch
@tanstack/query-sync-storage-persister	Patch
@tanstack/react-query	Patch
@tanstack/solid-query	Patch
@tanstack/svelte-query	Patch
@tanstack/vue-query	Patch
@tanstack/angular-query-persist-client	Patch
@tanstack/react-query-persist-client	Patch
@tanstack/solid-query-persist-client	Patch
@tanstack/svelte-query-persist-client	Patch
@tanstack/react-query-devtools	Patch
@tanstack/react-query-next-experimental	Patch
@tanstack/solid-query-devtools	Patch
@tanstack/svelte-query-devtools	Patch
@tanstack/vue-query-devtools	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

coderabbitai · 2025-11-05T13:30:23Z

Walkthrough

Introduces a changeset documenting a patch fix for @tanstack/query-core that wraps promise chains in dehydration with a no-op catch handler to suppress unhandled rejections on pending queries.

Changes

Cohort / File(s)	Summary
Changeset documentation `.changeset/little-berries-search.md`	Adds patch release notes documenting the fix for unhandled rejections on dehydrated promises
Hydration promise handling `packages/query-core/src/hydration.ts`	Refactors dehydration logic to wrap pending query promises in a `dehydratePromise` function with a local `catch(noop)` to suppress unhandled rejections while preserving correct result propagation

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12–15 minutes

Verify the dehydratePromise wrapper function correctly handles promise chains without introducing regressions
Confirm the no-op catch handler doesn't mask legitimate errors or alter promise resolution behavior
Check that dehydrated query results still propagate correctly through the cache

Possibly related PRs

Fix unhandled promise rejections during de/rehydration of pending queries #9752: Directly related change to packages/query-core/src/hydration.ts that adds a no-op catch around promises in dehydration/hydration to suppress unhandled rejections.

Poem

🐰 A promise once scattered and wild,
Now wrapped with a catch, gentle and mild,
No rejections left crying at night,
The hydration flows smooth—what a sight!

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description uses the correct template structure but lacks actual content in the 'Changes' section and all checklist items remain unchecked, including the required changeset generation.	Fill in the 'Changes' section with details about the fix and its motivation, and ensure checklist items (especially changeset generation) are properly completed and checked.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: only attaching .then and .catch callbacks to promises during dehydration, which aligns with the refactoring in hydration.ts.

✨ Finishing touches

📝 Generate docstrings

🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch feature/no-promise-dehydrate

📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a5fca0e and 033c868.

📒 Files selected for processing (2)

.changeset/little-berries-search.md (1 hunks)
packages/query-core/src/hydration.ts (2 hunks)

🧰 Additional context used

🧠 Learnings (3)

📓 Common learnings

Learnt from: TkDodo
Repo: TanStack/query PR: 9612
File: packages/query-async-storage-persister/src/asyncThrottle.ts:0-0
Timestamp: 2025-09-02T17:57:33.184Z
Learning: When importing from tanstack/query-core in other TanStack Query packages like query-async-storage-persister, a workspace dependency "tanstack/query-core": "workspace:*" needs to be added to the package.json.

📚 Learning: 2025-11-02T22:52:33.071Z

Learnt from: DogPawHat
Repo: TanStack/query PR: 9835
File: packages/query-core/src/__tests__/queryClient.test-d.tsx:242-256
Timestamp: 2025-11-02T22:52:33.071Z
Learning: In the TanStack Query codebase, the new `query` and `infiniteQuery` methods support the `select` option for data transformation, while the legacy `fetchQuery` and `fetchInfiniteQuery` methods do not support `select` and should reject it at the type level.

Applied to files:

packages/query-core/src/hydration.ts

📚 Learning: 2025-09-02T17:57:33.184Z

Learnt from: TkDodo
Repo: TanStack/query PR: 9612
File: packages/query-async-storage-persister/src/asyncThrottle.ts:0-0
Timestamp: 2025-09-02T17:57:33.184Z
Learning: When importing from tanstack/query-core in other TanStack Query packages like query-async-storage-persister, a workspace dependency "tanstack/query-core": "workspace:*" needs to be added to the package.json.

Applied to files:

.changeset/little-berries-search.md

🧬 Code graph analysis (1)

packages/query-core/src/hydration.ts (2)

packages/query-core/src/query.ts (1)
promise (198-200)
packages/query-core/src/utils.ts (1)
noop (82-82)

🔇 Additional comments (3)

packages/query-core/src/hydration.ts (2)
82-104: LGTM! Clean encapsulation of promise handling.
The dehydratePromise wrapper correctly:
Chains serialization via .then(serializeData)
Preserves error redaction logic with appropriate logging in development
Adds catch(noop) to suppress unhandled rejections while allowing the rejection to propagate to the query cache
This ensures promise handlers are only attached during dehydration, aligning with the PR objective.
116-118: LGTM! Correctly scoped promise dehydration.
The conditional application of dehydratePromise() only when query.state.status === 'pending' ensures promise handlers are attached only when needed, preventing unnecessary overhead and potential unhandled rejection warnings in non-dehydration scenarios.
.changeset/little-berries-search.md (1)
1-5: LGTM! Changeset correctly documents the fix.
The changeset appropriately declares a patch release for @tanstack/query-core with a description that matches the PR objective.

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nx-cloud · 2025-11-05T13:30:42Z

View your CI Pipeline Execution ↗ for commit 033c868

Command	Status	Duration	Result
`nx affected --targets=test:sherif,test:knip,tes...`	✅ Succeeded	45s	View ↗
`nx run-many --target=build --exclude=examples/*...`	✅ Succeeded	1s	View ↗

☁️ Nx Cloud last updated this comment at 2025-11-05 15:32:51 UTC

pkg-pr-new · 2025-11-05T13:33:03Z

More templates

@tanstack/angular-query-experimental

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@tanstack/eslint-plugin-query

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commit: 033c868

github-actions · 2025-11-05T13:33:05Z

Sizes for commit 033c868:

Branch	Bundle Size
Main
This PR

codecov · 2025-11-05T13:36:22Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.79%. Comparing base (a5fca0e) to head (033c868).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #9847 +/- ##
===========================================
+ Coverage 45.75% 59.79% +14.04% 
===========================================
Files 200 129 -71 Lines 8408 5624 -2784 Branches 1929 1525 -404 ===========================================
- Hits 3847 3363 -484 + Misses 4113 1956 -2157 + Partials 448 305 -143

Components	Coverage Δ
@tanstack/angular-query-experimental	`93.85% <ø> (ø)`
@tanstack/eslint-plugin-query	`∅ <ø> (∅)`
@tanstack/query-async-storage-persister	`43.85% <ø> (ø)`
@tanstack/query-broadcast-client-experimental	`24.39% <ø> (ø)`
@tanstack/query-codemods	`∅ <ø> (∅)`
@tanstack/query-core	`97.38% <100.00%> (+<0.01%)`	⬆️
@tanstack/query-devtools	`3.48% <ø> (ø)`
@tanstack/query-persist-client-core	`80.00% <ø> (ø)`
@tanstack/query-sync-storage-persister	`84.61% <ø> (ø)`
@tanstack/query-test-utils	`∅ <ø> (∅)`
@tanstack/react-query	`96.01% <ø> (ø)`
@tanstack/react-query-devtools	`10.00% <ø> (ø)`
@tanstack/react-query-next-experimental	`∅ <ø> (∅)`
@tanstack/react-query-persist-client	`100.00% <ø> (ø)`
@tanstack/solid-query	`77.81% <ø> (ø)`
@tanstack/solid-query-devtools	`61.90% <ø> (ø)`
@tanstack/solid-query-persist-client	`100.00% <ø> (ø)`
@tanstack/svelte-query	`∅ <ø> (∅)`
@tanstack/svelte-query-devtools	`∅ <ø> (∅)`
@tanstack/svelte-query-persist-client	`∅ <ø> (∅)`
@tanstack/vue-query	`71.10% <ø> (ø)`
@tanstack/vue-query-devtools	`∅ <ø> (∅)`

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Ensure .then and .catch are only attached to dehydrated promises.

Svish · 2025-11-05T15:32:44Z

@TkDodo Re request to try this out, I reverted our project to before I removed the cancellation token thing, and was able to get the same errors in the log. I then installed the preview-version from this PR, and as far as I can see, it seems there are no longer any errors in the log. So, from my point of view at least, this PR seems to fix the issue. 👍

fix(core): only attach .then and .catch onto a promise if it gets deh…
3341905
…ydrated

TkDodo requested a review from Ephem November 5, 2025 13:30

github-actionsBot added the package: query-core label Nov 5, 2025

TkDodo marked this pull request as ready for review November 5, 2025 15:30

Fix promise handling in core for dehydrated states
033c868
Ensure .then and .catch are only attached to dehydrated promises.

Svish approved these changes Nov 5, 2025
View reviewed changes

TkDodo merged commit b4cd121 into mainNov 5, 2025
9 checks passed

TkDodo deleted the feature/no-promise-dehydrate branch November 5, 2025 15:44

github-actionsBot mentioned this pull request Nov 5, 2025
ci: Version Packages #9848
Merged

coderabbitaiBot mentioned this pull request Jan 27, 2026
Fix/infinite query hydration 8825 #10074
Merged
5 tasks

coderabbitaiBot mentioned this pull request Feb 8, 2026
fix(solid-query): strip promise field in hydratableObserverResult to … #10104
Open
4 tasks

coderabbitaiBot mentioned this pull request Feb 21, 2026
Prevent useQuery from skipping hydration #10159
Open
4 tasks

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fix(core): only attach .then and .catch onto a promise if it gets dehydrated - #9847

fix(core): only attach .then and .catch onto a promise if it gets dehydrated#9847
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