From 239858a8590c09d82d4662aafcd1de515c2886de Mon Sep 17 00:00:00 2001
From: Josh Story <gnoff@storyposted.com>
Date: Fri, 29 May 2026 15:57:54 -0700
Subject: [PATCH] [Fizz] Do not allow abort reentrancy

Aborting is a gate you can only pass through once. A request that is already aborting, already completed, or already fatalled cannot be aborted a second time. Previously this was generally functionally true but you could contrive sequences where an onError would fire after a render fataled. This change makes it more explicit that this is not semantically correct by bailing out of abort if the request is in a status that cannot be aborted.
---
 .../src/__tests__/ReactDOMFizzServer-test.js  | 44 +++++++++++++++++--
 .../__tests__/ReactDOMFizzServerNode-test.js  | 36 +++++++++++++--
 packages/react-server/src/ReactFizzServer.js  |  7 ++-
 3 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js b/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js
index efb7e887cf18..3ef1db6e7453 100644
--- a/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js
@@ -4003,10 +4003,46 @@ describe('ReactDOMFizzServer', () => {
     await act(() => pipe(testWritable));
     expect(didRender).toBe(false);
     expect(didFatal).toBe(didFatal);
-    expect(errors).toEqual([
-      'boom',
-      'The destination stream errored while writing data.',
-    ]);
+    expect(errors).toEqual(['boom']);
+  });
+
+  it('does not report aborts after fatally erroring', async () => {
+    const promise = new Promise(() => {});
+    function AsyncComp() {
+      React.use(promise);
+      return 'Async';
+    }
+
+    function ErrorComp() {
+      throw new Error('boom');
+    }
+
+    const errors = [];
+    let abort;
+    await act(() => {
+      abort = renderToPipeableStream(
+        <div>
+          <Suspense fallback="loading...">
+            <AsyncComp />
+          </Suspense>
+          <ErrorComp />
+        </div>,
+        {
+          onError(error) {
+            errors.push(error.message);
+          },
+          onShellError() {},
+        },
+      ).abort;
+    });
+
+    expect(errors).toEqual(['boom']);
+
+    await act(() => {
+      abort(new Error('too late'));
+    });
+
+    expect(errors).toEqual(['boom']);
   });
 
   describe('error escaping', () => {
diff --git a/packages/react-dom/src/__tests__/ReactDOMFizzServerNode-test.js b/packages/react-dom/src/__tests__/ReactDOMFizzServerNode-test.js
index 98030d43386c..c3554c757df2 100644
--- a/packages/react-dom/src/__tests__/ReactDOMFizzServerNode-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMFizzServerNode-test.js
@@ -237,6 +237,37 @@ describe('ReactDOMFizzServerNode', () => {
     expect(reportedShellErrors).toEqual([theError]);
   });
 
+  it('should not report aborts after the shell has fatally errored', async () => {
+    const reportedErrors = [];
+    const reportedShellErrors = [];
+    const {abort} = ReactDOMFizzServer.renderToPipeableStream(
+      <div>
+        <Suspense fallback="Loading">
+          <InfiniteSuspend />
+        </Suspense>
+        <Throw />
+      </div>,
+      {
+        onError(x) {
+          reportedErrors.push(x);
+        },
+        onShellError(x) {
+          reportedShellErrors.push(x);
+        },
+      },
+    );
+
+    await jest.runAllTimers();
+
+    expect(reportedErrors).toEqual([theError]);
+    expect(reportedShellErrors).toEqual([theError]);
+
+    abort(new Error('too late'));
+
+    expect(reportedErrors).toEqual([theError]);
+    expect(reportedShellErrors).toEqual([theError]);
+  });
+
   it('should error the stream when an error is thrown inside a fallback', async () => {
     const reportedErrors = [];
     const reportedShellErrors = [];
@@ -263,10 +294,7 @@ describe('ReactDOMFizzServerNode', () => {
 
     expect(output.error).toBe(theError);
     expect(output.result).toBe('');
-    expect(reportedErrors).toEqual([
-      theError.message,
-      'The destination stream errored while writing data.',
-    ]);
+    expect(reportedErrors).toEqual([theError.message]);
     expect(reportedShellErrors).toEqual([theError]);
   });
 
diff --git a/packages/react-server/src/ReactFizzServer.js b/packages/react-server/src/ReactFizzServer.js
index 73b3e435d189..3320d545b153 100644
--- a/packages/react-server/src/ReactFizzServer.js
+++ b/packages/react-server/src/ReactFizzServer.js
@@ -6143,9 +6143,12 @@ export function stopFlowing(request: Request): void {
 
 // This is called to early terminate a request. It puts all pending boundaries in client rendered state.
 export function abort(request: Request, reason: mixed): void {
-  if (request.status === OPEN || request.status === OPENING) {
-    request.status = ABORTING;
+  if (request.status !== OPEN && request.status !== OPENING) {
+    // Only requests that are not already complete or in the process of aborting
+    // can be aborted. in practice this makes abort callable at most once per render.
+    return;
   }
+  request.status = ABORTING;
 
   try {
     const abortableTasks = request.abortableTasks;