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[Fiber] Fix context propagation into Suspense fallbacks - #36160

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acdlite merged 1 commit into
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acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged

[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom
acdlite:fallback-context-propagation-fix

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@acdliteacdlite commented Mar 27, 2026

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Summary

When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.

propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).

The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.

In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.

Test plan

  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass

@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite marked this pull request as ready for review March 27, 2026 21:53
@github-actionsgithub-actionsBot added the React Core Team Opened by a member of the React Core Team label Mar 27, 2026
@react-sizebot

react-sizebot commented Mar 27, 2026

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Comparing: 2233b7d...20d7378

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 20d7378

@acdlite
acdlite requested review from eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon changed the title Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon approved these changes Mar 27, 2026•
edited
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@acdlite
acdlite merged commit 9627b5a into react:mainMar 27, 2026
245 checks passed
github-actionsBot pushed a commit that referenced this pull request Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot pushed a commit that referenced this pull request Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot mentioned this pull request Mar 27, 2026
Merged
acdlite pushed a commit to vercel/next.js that referenced this pull request Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot pushed a commit to code/lib-react that referenced this pull request Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot pushed a commit to code/lib-react that referenced this pull request Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte mentioned this pull request Jun 5, 2026
Closed
m-kawafuji pushed a commit to m-kawafuji/next.js that referenced this pull request Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@eps1loneps1loneps1lon approved these changes
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@acdlite@react-sizebot@eps1lon
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btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
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var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
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try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

Copy link


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Collaborator
Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
added
the 
React Core Team
Opened by a member of the React Core Team
label
Mar 27, 2026
@react-sizebot
react-sizebot
commented
Mar 27, 2026

Copy link


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Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@eps1loneps1loneps1lon approved these changes
@gnoffgnoffAwaiting requested review from gnoff

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@acdlite@react-sizebot@eps1lon

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
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var __m = "*";
var __re = new RegExp('^' + ".*" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
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@acdlite
@acdliteacdlite
commented
Mar 27, 2026

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Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
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Opened by a member of the React Core Team
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Mar 27, 2026
@react-sizebot
react-sizebot
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Mar 27, 2026

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Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@acdlite@react-sizebot@eps1lon

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Array.from(node.childNodes).forEach(highlight);
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mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
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observer.observe(document.body, { childList: true, subtree: true });
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})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

Copy link


Copy Markdown

Collaborator
Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
added
the 
React Core Team
Opened by a member of the React Core Team
label
Mar 27, 2026
@react-sizebot
react-sizebot
commented
Mar 27, 2026

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Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@acdlite@react-sizebot@eps1lon

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

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Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
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Opened by a member of the React Core Team
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Mar 27, 2026
@react-sizebot
react-sizebot
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Mar 27, 2026

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Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
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@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@eps1loneps1loneps1lon approved these changes
@gnoffgnoffAwaiting requested review from gnoff

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3 participants

@acdlite@react-sizebot@eps1lon

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

Copy link


Copy Markdown

Collaborator
Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
added
the 
React Core Team
Opened by a member of the React Core Team
label
Mar 27, 2026
@react-sizebot
react-sizebot
commented
Mar 27, 2026

Copy link


Copy Markdown

Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@acdlite@react-sizebot@eps1lon

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

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Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
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Opened by a member of the React Core Team
label
Mar 27, 2026
@react-sizebot
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Mar 27, 2026

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Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
Sign up for freeto join this conversation on GitHub.
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@eps1loneps1loneps1lon approved these changes
@gnoffgnoffAwaiting requested review from gnoff

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3 participants

@acdlite@react-sizebot@eps1lon

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
[Fiber] Fix context propagation into Suspense fallbacks by acdlite · Pull Request #36160 · react/react · GitHub
Skip to content
[Fiber] Fix context propagation into Suspense fallbacks - #36160
Merged
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Mar 27, 2026
Merged
[Fiber] Fix context propagation into Suspense fallbacks#36160
acdlite merged 1 commit into
react:mainfrom 
acdlite:fallback-context-propagation-fix
Conversation
@acdlite
@acdliteacdlite
commented
Mar 27, 2026

Copy link


Copy Markdown

Collaborator
Summary
When a context value changes above a Suspense boundary that is showing its fallback, context consumers inside the fallback do not re-render — they display stale values.
propagateContextChanges, upon encountering a suspended Suspense boundary, marks the boundary for retry but stops traversing into its children entirely (nextFiber = null). This skips both the hidden primary subtree (intentional — those fibers may not exist) and the visible fallback subtree (a bug — those fibers are committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal into the FallbackFragment, so fallback context consumers are found and marked for re-render.
In practice this often goes unnoticed because it's uncommon to read context inside a Suspense fallback, and when some other update (like a prop change) flows into the fallback it sidesteps the propagation path entirely. React Compiler makes the bug more likely to surface since it memoizes more aggressively, reducing the chance of an incidental re-render masking the stale value.
Test plan
  • Added regression test 'context change propagates to Suspense fallback (memo boundary)' in ReactContextPropagation-test.js
  • Verified the test fails without the fix and passes with it
  • All existing context propagation, Suspense, memo, and hooks tests pass
@acdlite
Fix context propagation into Suspense fallbacks
20d7378
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render.
They continue to display stale values.
This happens because `propagateContextChanges`, upon encountering a
suspended Suspense boundary, marks the boundary for retry but stops
traversing into its children entirely (`nextFiber = null`). This skips
both the hidden primary subtree (intentional — those fibers may not
exist) and the visible fallback subtree (a bug — those fibers are
committed and visible to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
@acdlite
acdlite
marked this pull request as ready for review
March 27, 2026 21:53
@github-actionsgithub-actionsBot
added
the 
React Core Team
Opened by a member of the React Core Team
label
Mar 27, 2026
@react-sizebot
react-sizebot
commented
Mar 27, 2026

Copy link


Copy Markdown

Comparing: 2233b7d...20d7378
Critical size changes
Includes critical production bundles, as well as any change greater than 2%:
Name+/-BaseCurrent+/- gzipBase gzipCurrent gzip
oss-stable/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB+0.05%1.88 kB1.88 kB
oss-stable/react-dom/cjs/react-dom-client.production.js=612.88 kB612.91 kB=108.30 kB108.30 kB
oss-experimental/react-dom/cjs/react-dom.production.js=6.84 kB6.84 kB=1.88 kB1.88 kB
oss-experimental/react-dom/cjs/react-dom-client.production.js=678.81 kB678.85 kB=119.26 kB119.27 kB
facebook-www/ReactDOM-prod.classic.js=698.20 kB698.24 kB=122.65 kB122.65 kB
facebook-www/ReactDOM-prod.modern.js=688.52 kB688.55 kB=121.03 kB121.03 kB
Significant size changes
Includes any change greater than 0.2%:
(No significant changes)

Generated by 🚫 dangerJS against 20d7378
@acdlite
acdlite
requested review from
eps1lon and gnoffMarch 27, 2026 22:01
@eps1loneps1lon
changed the title
Fix context propagation into Suspense fallbacks[Fiber] Fix context propagation into Suspense fallbacksMar 27, 2026
eps1lon
eps1lon
approved these changes
Mar 27, 2026•

edited

Loading
View reviewed changes
@acdlite
acdlite
merged commit 9627b5a
into
react:mainMar 27, 2026

245 checks passed

github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
7aa5907
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
github-actionsBot
pushed a commit
that referenced
this pull request
Mar 27, 2026
@acdlite
[Fiber] Fix context propagation into Suspense fallbacks (#36160)
0204304
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](9627b5a)
@nextjs-botnextjs-bot
mentioned this pull request
Mar 27, 2026
 Merged

acdlite pushed a commit
to vercel/next.js
that referenced
this pull request
Mar 28, 2026
@nextjs-bot@eps1lon
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(#92015)
d8b5ea2
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
7371e98
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
github-actionsBot
pushed a commit
to code/lib-react
that referenced
this pull request
Mar 30, 2026
@pull
[Fiber] Fix context propagation into Suspense fallbacks (react#36160)
45be1d8
## Summary
When a context value changes above a Suspense boundary that is showing
its fallback, context consumers inside the fallback do not re-render —
they display stale values.
`propagateContextChanges`, upon encountering a suspended Suspense
boundary, marks the boundary for retry but stops traversing into its
children entirely (`nextFiber = null`). This skips both the hidden
primary subtree (intentional — those fibers may not exist) and the
visible fallback subtree (a bug — those fibers are committed and visible
to the user).
The fix skips the primary OffscreenComponent and continues traversal
into the FallbackFragment, so fallback context consumers are found and
marked for re-render.
In practice this often goes unnoticed because it's uncommon to read
context inside a Suspense fallback, and when some other update (like a
prop change) flows into the fallback it sidesteps the propagation path
entirely. React Compiler makes the bug more likely to surface since it
memoizes more aggressively, reducing the chance of an incidental
re-render masking the stale value.
## Test plan
- Added regression test `'context change propagates to Suspense fallback
(memo boundary)'` in `ReactContextPropagation-test.js`
- Verified the test fails without the fix and passes with it
- All existing context propagation, Suspense, memo, and hooks tests pass
DiffTrain build for [9627b5a](react@9627b5a)
@rubennorterubennorte
mentioned this pull request
Jun 5, 2026
 Closed

m-kawafuji pushed a commit
to m-kawafuji/next.js
that referenced
this pull request
Aug 8, 2026
@nextjs-bot@eps1lon@m-kawafuji
Upgrade React from3cb2c420-20260324to9627b5a1-20260327(vercel…
cdaaf02
…#92015)
[diff
react/react@3cb2c420...9627b5a1](react/react@3cb2c42...9627b5a)
<details>
<summary>React upstream changes</summary>
- react/react#36160
- react/react#35701
- react/react#35627
- react/react#35621
- react/react#35623
</details>
---------
Co-authored-by: Sebastian Sebbie Silbermann <sebastian.silbermann@vercel.com>
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@eps1loneps1loneps1lon approved these changes
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