A small, inspectable workaround for @tanstack/form-core 1.33.5 when an older asynchronous field check finishes while a newer check is still pending. It includes executable regression checks against the real Form API, for both ESM and CommonJS.
The need comes from TanStack Form #2045. The issue author already has an upstream PR, #2047. This separate patch targets the published 1.33.5 package; it is not that PR and does not imply upstream acceptance. Check the upstream issue and release notes before adopting it on a newer version.
Download the source ZIP, extract it, then run:
cd tanstack-validation-state
npm ci --ignore-scripts
npm testUse Node.js 22 or newer and Git. The fixture pins its official dependency and records the dependency tree in package-lock.json. All validation values and responses are synthetic; no real account or remote validation service is used.
To see the regression in the original package:
npm run reproduceThis command deliberately exits with a failure when the original package violates the expected behavior. npm test applies the patch to a temporary copy and runs the same behavioral checks against the patched package. A failing original reproduction is expected; a failing patched run needs investigation.
The verifier checks the exact package version and original source hashes before copying or applying anything. It creates a unique .verification-* directory beside this example and removes its own directory afterward, including on failure. It does not patch your original node_modules. Verification makes no network requests; installing dependencies requires access to the npm registry.
The field-validation code keeps a handle for its debounce timer. In the affected version, a handle remains stored after the timer has fired and started its checker. Starting another check can therefore count that earlier, already-running check as cancelled; when the earlier promise actually settles, the pending count is reduced again.
The patch clears the stored handle when the timer callback starts. Cancelling a timer that is still waiting retains the existing behavior, and a running check retains its existing settlement path. The patch also publishes the form's aggregate isValidating value from field or form validation activity, and uses that value for the existing canSubmit calculation.
Matching shipped TypeScript source, ESM runtime and CommonJS runtime files are patched. Changed runtime files no longer refer to their original source maps, because the edits invalidate those mappings. Public signatures and the existing pending-counter mechanism are retained.
First run the independent example above. Its success verifies this fixture's installed package; it does not prove your application's lockfile resolves the same package or that your framework adapter loads that copy.
Pin the affected dependency in your application and inspect the resolved tree:
npm install --save-exact @tanstack/form-core@1.33.5
npm ls @tanstack/form-coreIf you use a framework adapter, confirm it resolves the same 1.33.5 copy you intend to patch. A nested copy or another version needs its own compatibility assessment. This example does not override your adapter's dependency requirements.
Before applying the patch, compare the SHA-256 hashes of the six files listed in EXPECTED_HASHES near the top of verify.mjs with your installed files under node_modules/@tanstack/form-core. Stop if the version or any hash differs. An already modified installation is outside this fixture's supported scope.
Copy patches/@tanstack+form-core+1.33.5.patch into your application's patches directory. From the application root containing node_modules, inspect the patch and check that it applies before making the change:
git apply --check patches/@tanstack+form-core+1.33.5.patch
git apply patches/@tanstack+form-core+1.33.5.patchgit apply --check checks patch context, not every byte of every file; it does not replace the version and hash comparison above.
Run your application's validation and submission checks afterward. Reinstalling dependencies can overwrite a manual patch. If your application already uses patch-package, the patch uses its conventional node_modules paths and filename; arrange reapplication through your application's own install workflow. This repository does not add a postinstall hook or alter your application's configuration.
The example uses mounted FormApi and FieldApi instances and controllable promises. It exercises old-first and latest-first completion with and without debounce, an old checker that ignores cancellation, independent fields, linked-field validation, a form-level asynchronous validator, idle behavior and changes that supersede a timer before it starts. Assertions read public field and form state. All 18 scenarios pass on the patched copy with Node.js 24.19.0, including a fresh install from the source ZIP.
The pending indicator must remain true while the newer check is in flight, and the latest result must own the displayed field error after settlement. Form-level activity contributes to the aggregate indicator. The fixture checks Node ESM and CommonJS execution; it does not establish native browser rendering or every framework adapter's behavior, nor fix every possible form-level validation lifecycle problem.
MIT, including the original TanStack Form copyright notice. You may use, modify and share the patch and fixture while retaining the notices.
If this saved you a little time, you're welcome to buy me a coffee. Please don't feel obliged — the code stays free, and feedback with a small reproducible example is appreciated too.
- USDC / SOL · Solana:
9tY6D9mwcFaJwwzEHvw2v7nhSpdjqjNBYtuooyBN6rYy - USDC / ETH · Base:
0x568Ab98578d682FB0B0b45619BE73EbFfbf5a6eA - USDT · BNB Smart Chain (BEP20):
0x568Ab98578d682FB0B0b45619BE73EbFfbf5a6eA
Please match the asset and network exactly. Fees depend on your wallet or exchange. Thank you! — Tevinch