From a0441e4e38969065c753046f68ec5954e8158ee9 Mon Sep 17 00:00:00 2001
From: Burak Keskin <official.burak@icloud.com>
Date: Wed, 19 Aug 2026 20:55:53 +0300
Subject: [PATCH 1/2] fix(form-core): ignore aborted async form-level
 validation results

FieldApi and FormGroupApi already drop in-flight async results after a newer run aborts them. FormApi was missing that check, so a slower previous validator could overwrite newer valid state.
---
 .changeset/quiet-forms-ignore-stale.md   |  5 ++++
 packages/form-core/src/FormApi.ts        |  1 +
 packages/form-core/tests/FormApi.spec.ts | 38 ++++++++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 .changeset/quiet-forms-ignore-stale.md

diff --git a/.changeset/quiet-forms-ignore-stale.md b/.changeset/quiet-forms-ignore-stale.md
new file mode 100644
index 000000000..ed05e7de2
--- /dev/null
+++ b/.changeset/quiet-forms-ignore-stale.md
@@ -0,0 +1,5 @@
+---
+"@tanstack/form-core": patch
+---
+
+Ignore aborted async form-level validation results so a slower previous run cannot overwrite newer form state.
diff --git a/packages/form-core/src/FormApi.ts b/packages/form-core/src/FormApi.ts
index 4400017d3..3315639d9 100644
--- a/packages/form-core/src/FormApi.ts
+++ b/packages/form-core/src/FormApi.ts
@@ -2232,6 +2232,7 @@ export class FormApi<
           } catch (e: unknown) {
             rawError = e as ValidationError
           }
+          if (controller.signal.aborted) return resolve(undefined)
           const { formError, fieldErrors: fieldErrorsFromNormalizeError } =
             normalizeError<TFormData>(rawError)
 
diff --git a/packages/form-core/tests/FormApi.spec.ts b/packages/form-core/tests/FormApi.spec.ts
index c57bb044e..46d18fea4 100644
--- a/packages/form-core/tests/FormApi.spec.ts
+++ b/packages/form-core/tests/FormApi.spec.ts
@@ -1420,6 +1420,44 @@ describe('form api', () => {
     })
   })
 
+  it('should ignore aborted async form-level validation results', async () => {
+    vi.useFakeTimers()
+
+    const form = new FormApi({
+      defaultValues: {
+        name: 'valid',
+      },
+      validators: {
+        onChangeAsyncDebounceMs: 0,
+        onChangeAsync: async ({ value }) => {
+          if (value.name === 'slow-invalid') {
+            await sleep(2000)
+            return 'Stale validation result'
+          }
+          await sleep(50)
+          return undefined
+        },
+      },
+    })
+    const field = new FieldApi({
+      form,
+      name: 'name',
+    })
+    form.mount()
+    field.mount()
+
+    field.setValue('slow-invalid')
+    await vi.advanceTimersByTimeAsync(0)
+    field.setValue('valid')
+    await vi.advanceTimersByTimeAsync(50)
+    expect(form.state.errors).toEqual([])
+
+    await vi.advanceTimersByTimeAsync(2000)
+    expect(form.state.errors).toEqual([])
+    expect(form.state.errorMap.onChange).toBeUndefined()
+    vi.useRealTimers()
+  })
+
   it('should run validation onBlur', () => {
     const form = new FormApi({
       defaultValues: {

From e7272c9eb99c1b581b9b7a8271aa3020f3c1ffa7 Mon Sep 17 00:00:00 2001
From: Burak Keskin <official.burak@icloud.com>
Date: Tue, 20 Oct 2026 16:09:03 +0300
Subject: [PATCH 2/2] Restore real timers even when the aborted validation test
 fails

---
 packages/form-core/tests/FormApi.spec.ts | 67 +++++++++++++-----------
 1 file changed, 35 insertions(+), 32 deletions(-)

diff --git a/packages/form-core/tests/FormApi.spec.ts b/packages/form-core/tests/FormApi.spec.ts
index 46d18fea4..318f38e45 100644
--- a/packages/form-core/tests/FormApi.spec.ts
+++ b/packages/form-core/tests/FormApi.spec.ts
@@ -1423,39 +1423,42 @@ describe('form api', () => {
   it('should ignore aborted async form-level validation results', async () => {
     vi.useFakeTimers()
 
-    const form = new FormApi({
-      defaultValues: {
-        name: 'valid',
-      },
-      validators: {
-        onChangeAsyncDebounceMs: 0,
-        onChangeAsync: async ({ value }) => {
-          if (value.name === 'slow-invalid') {
-            await sleep(2000)
-            return 'Stale validation result'
-          }
-          await sleep(50)
-          return undefined
+    try {
+      const form = new FormApi({
+        defaultValues: {
+          name: 'valid',
         },
-      },
-    })
-    const field = new FieldApi({
-      form,
-      name: 'name',
-    })
-    form.mount()
-    field.mount()
-
-    field.setValue('slow-invalid')
-    await vi.advanceTimersByTimeAsync(0)
-    field.setValue('valid')
-    await vi.advanceTimersByTimeAsync(50)
-    expect(form.state.errors).toEqual([])
-
-    await vi.advanceTimersByTimeAsync(2000)
-    expect(form.state.errors).toEqual([])
-    expect(form.state.errorMap.onChange).toBeUndefined()
-    vi.useRealTimers()
+        validators: {
+          onChangeAsyncDebounceMs: 0,
+          onChangeAsync: async ({ value }) => {
+            if (value.name === 'slow-invalid') {
+              await sleep(2000)
+              return 'Stale validation result'
+            }
+            await sleep(50)
+            return undefined
+          },
+        },
+      })
+      const field = new FieldApi({
+        form,
+        name: 'name',
+      })
+      form.mount()
+      field.mount()
+
+      field.setValue('slow-invalid')
+      await vi.advanceTimersByTimeAsync(0)
+      field.setValue('valid')
+      await vi.advanceTimersByTimeAsync(50)
+      expect(form.state.errors).toEqual([])
+
+      await vi.advanceTimersByTimeAsync(2000)
+      expect(form.state.errors).toEqual([])
+      expect(form.state.errorMap.onChange).toBeUndefined()
+    } finally {
+      vi.useRealTimers()
+    }
   })
 
   it('should run validation onBlur', () => {