refactor: move HtmlContext: #34482
rsc: clean client buffer cache after flushed: #34475
Ensure config's experimental field exists: #34500
Only log experiments warning if user actually opted in to an experiment(s): #34413
Add unstable_useFlushEffects hook: #34117
fix: mock image path as next/image expects it: #34350
fix process polyfill on middleware: #34426
Ensure workers are not left open: #34503
Leverage existing component checking warning for streaming: #34526
build(next-swc): linux glibc compatible issue:

Release notes available: 1
Commit history only: 0
History missing: 0

Last checked 2 Oct 2026, 11:00 UTC

Checking sources…

12.1.1

Breaking signals25 Mar 2022GitHub Release

Additional changes to review3Matched wording:removeddeprecatedrenamedThese matches may be harmless in context. Expand to see the excerpts.

The changelog contains “removed”; check what was removed.
Typo in URL removed: #35472
The changelog mentions deprecation; it may still be compatible.
chore: replace deprecated String.prototype.substr():

Core Changes

refactor: move HtmlContext: #34482
rsc: clean client buffer cache after flushed: #34475
Ensure config's experimental field exists: #34500
Only log experiments warning if user actually opted in to an experiment(s): #34413
Add unstable_useFlushEffects hook: #34117
fix: mock image path as next/image expects it: #34350
fix process polyfill on middleware: #34426
Ensure workers are not left open: #34503
Leverage existing component checking warning for streaming: #34526
build(next-swc): linux glibc compatible issue:

#35421

The changelog contains “renamed”; check whether a public API changed.

Update CODEOWNERS to include renamed files: #34686

#34481

Fix next/image incorrectly warning for position: absolute parent: #34551

Remove useMaybeDeferContent hook: #34506

Allow reading request bodies in middlewares (#34294): #34519

Update swc crates: #34491

feat(react-dev-overlay): export getErrorByType and add preventDisplay prop: #34237

Improve next/image warnings to avoid printing more than once: #34562

Support trailingSlash in middleware SSR: #34544

Update to latest version of jscodeshift: #34563

Don't import internally from types in next-env.d.ts: #34394

Improve type imports in server/render and optimize the Edge SSR loader: #34552

remove commons chunk config: #34445

Add cargo clippy and cargo fmt to CI: #34625

Fix rsc bootstrap buffer missing in the future renders: #34631

fix: match redirect and rewrite destination types: #34617

fix: make sure image-config.ts gets transpiled to ES5: #34677

Normalize image optimizer error status codes: #34699

Fix CSS Loader Detection False Positives: #34584

Upgrade @napi-rs/triples to support android arm platform: #34752

Add proper headers to responses in web server: #34723

produce source maps for middlewares: #34409

Reduce the size of web server: #34767

collect telemetry for ESLint rules: #34564

Refactor entries generation in hot-reloader: #34733

Integrate tsec into the linting process: #33746

Add API config to allow disabling response size warning: #34700

fix(#34030): ignore non-checkable jsx spread attribute: #34473

fix eslint-plugin-react version to avoid jsx-key error: #34800

fix: #34711 ensure distDir inside project folder: #34795

Update to ncc dev overlay during build instead of pre-compile: #34813

Add warning for Yarn PnP v3 with Node.js < 16.14: #34818

lock eslint-config-next dependencies: #34823

Clean-up error when starting next with non-existent dir: #34830

Ensure unstable_revalidate does not error from notFound: true: #34826

Update eslint-plugin-react to latest version: #34819

Add CLI command typo detection: #34836

Fix flight loader for shared components: #34692

refactor: re-use existed escapeRegex: #34470

Fix only byte stream writing is allowed in CF workers: #34893

Only warn styles and scripts under next head in concurrent mode: #34897

Fix image optimization invalid internal upstream image: #34899

feat(next-swc): Update swc: #34878

Simplify next-flight-server-loader: #34902

Ensure non-matching API routes can be rewritten: #33966

Optimize component type filters: #34941

Expose WASM bindings in Middleware: #34437

Provide page runtime parsing utils: #34922

Refactor export marks of server components: #34945

Fix next/image noscript when blur and priority: #34973

Fix named export missing from client components: #34974

Adopt react 18 rc1: #34972

Fix typescript 4.6.2 randomUUID(): #34976

Update ISR error handling: #34931

Handle de-duping revalidations in minimal mode: #34935

feat: allow dotenv default expansion: #34765

Support colons in Middleware NextResponse.rewrite path: #32543

Generate static html for bots: #35004

Enable import assertion syntax parsing: #33750

Split up & tweak next/client initialization: #33838

Normalize root path according to trailingSlash option in default next/image loader #21337: #22453

Fix animated png bypass from Image Optimization API: #35120

watch node_modules: #35140

feat(trace): postprocess trace reporter for datadog: #35032

[next] Fix to not call middleware with shallow push, fix middleware call wit…: #35047

fix post request hangs when no body is consumed on middleware: #35131

fix: hard-navigate when preflight request fails: #35145

Per-page runtime: #35011

Delay prefix flushing: #35170

Change to loadBindings for swc parse: #35171

Ensure mjs files are transformed with jest: #34698

Disable the functions manifest plugin: #35155

Adopt react 18 rc2: #35161

Convert server.js to module.exports: #35181

Fix next/image when src is webp but browser doesnt support it: #35190

[Fix] Adds try/catch to gracefully handle performance observer exception: #35202

Render resolved streaming content for static render result: #35221

feat(next-swc): Update crates: #35133

Ensure that pages manifest contains pages of both runtimes: #35243

chore: upgrade cssnano-simple: #35258

fix(Script): allow passing defer=false to Script component: #34850

Remove the special _document-concurrent component: #35242

Adds web worker support to <Script /> using Partytown: #34244

Bump styled-jsx to 5.0.1: #35290

Add new 'raw' image layout: #34339

SWC emotion transform plugin: #34687

enhance: cover re-exported gsp cases for runtime fallback: #35326

Make concurrent features independent from the global runtime option: #35245

Update comments for the web server: #35366

Add libc fields to Linux platform packages: #35354

Drop browser field for edge runtime: #35335

Make router able to navigate between rsc pages: #35344

Revert "Make concurrent features independent from the global runtime option": #35405

Update on-demand ISR to skip fetch locally: #35386

Use hasConcurrentFeatures instead of reactRoot as the condition of Fizz: #35407

Abstract out stream related utils from render and web/utils: #35372

Keep fouc tags for streaming: #35417

Fix: change the timing for clearing the inlined data buffer: #35413

fix(document): accepts nodearray for head's children: #35424

Update to latest @vercel/nft and leverage new reason types: #35446

Add test to ensure fs.readFile() works with Output File Tracing: #35338

feat(next-swc): embed target triple string: #35416

Typo in URL removed: #35472

feat(telemetry): report swc target triple to telemetry: #35420

Update trace ignore check to check reasons correctly: #35511

SWC import modularization plugin: #34969

Reduce hello-world middleware bundle size from 128k to 88k: #35512

Update next/link error when no children are provided: #35453

Normalize ssgCacheKey for /index with minimalMode de-duping: #35536

Merge rsc queries handling: #35545

Upgrade react-server-dom-webpack: #35524

Fix styled transform in next-swc/emotion: #35527

Fix next info accidentally printing stderr: #35556

chore: replace deprecated String.prototype.substr(): #35421

test: warn on substr() usage: #35499

Documentation Changes

Update docs for image optimization swr: #34483
Fix 404 links in React 18 docs: #34486
Fix snippet language sh -> bash: #34487
Add info on rendering an error page when using getServerSideProps: #34488
Update details about Cache Control Headers: #34416
Update wrong code snippet: #34520
fix: change showcase url: #34590
Add note about public folder with standalone mode: #34646
added styled-components & replay support in swc: #34647
Provide more detail to static folder placement: #34651
Update testing.md: #34661
Remove page-specific font example from docs: #34694
Fix typo in documentation: #34734
Improve rewrites documentation: #34725
Add Error Handling document: #34329
Update inlineCode reference: #34817
Add redirect for error doc rename: #34791
Fix issues in getStaticPaths docs: #34840
Improve TypeScript documentation.: #34690
Fix broken link in react-18 streaming docs.: #34884
Add missing closing parenthesis in docs: #34924
[examples] Update styled-components to use SWC: #34770
feat: support pnpm with create-next-app: #34947
Fix missing parenthesis for link in docs: #35090
Update shallow routing caveat: #35052
Add next/image docs section for animated images: #35123
Add info on context.ctx argument in _app docs page: #35303
Encourage installation of sass as a devDep: #35323
[docs] Update docs about Cache-Control default headers.: #35336
[docs] Update going to production docs around caching headers: #35374
Update next/image docs for width & height: #35188
Added note about why Next.js used 307 and 308 status codes: #35325
Fix typo in getServerSideProps doc page: #35467
clarify use of Script: #35491
Server component docs use wrong next version: #35313
Add link for revalidate from notFound section: #35553
Fix typo in docs: #35561

Example Changes

Convert custom-server-hapi Example to Typescript: #34507
Updated head, img -> Image, type { NextPage } as default next-app: #34513
removing redundant/unnecessary lines as these are defaults: #34587
Sentry example: add js types to SentryWebpackPluginOptions: #28726
Add .git to .dockerignore in docker examples: #34628
Updates with-supertokens example: #34679
Convert with-redis example to TypeScript: #34720
Update MySQL example.: #34784
Some minor adjustments to MySQL example.: #34792
docs: update CMS examples to use the new tw grid gaps: #34917
docs: update cms-sanity example: #34898
Update cms-wordpress example: #34944
Update supertokens demo app: #35007
fix(examples/with-docker): add npm comment for yarn build: #35040
[examples] Add Tina CMS blog starter: #35045
[examples] Use more semantic footer element: #35033
Re-add _document to with-styled-components example: #35163
docs(examples): add on-demand ISR to cms-sanity: #35220
examples: update instructions for create-strapi-app: #35288
Remove with-custom-reverse-proxy example: #35340
Change README structure in examples: #35349
use initial state for rootReducer in with-redux-saga example: #35406

Misc Changes

chore: clarify GitHub action (bot) comments: #34546
Add test for multiple cookies coming from middleware: #34465
Simplify .env.local gitignores: #34471
Clarify test types during scaffolding: #34638
Ensure rust-check skips on docs only change: #34648
Update CODEOWNERS to include renamed files: #34686
Lock yarn pnp version in tests: #34688
Fix create-next-app Multiple calls to the function 'makeDir': #34669
chore: Move test for streaming and RSC: #34724
Fix react-dom type error in CNA typescript template: #34623
Update test concurrency for CI: #34827
Update to use whatwg validator for test: #34891
dep: upgrade @swc/core v1.2.148 , @swc/cli v0.1.55: #35054
Run tests against node LTS (v16) and current (v17): #35414
test: add document head multi child prod test: #35426
Use check on prerender test assertion: #35482

Credits

Huge thanks to @styfle, @shuding, @balazsorban44, @huozhi, @amandeepmittal, @bennettdams, @sophiabits, @MaedahBatool, @devknoll, @nkzawa, @kinetifex, @elrumordelaluz, @Brooooooklyn, @mitchell-abbott, @Schniz, @natew, @nrjdalal, @dephraiim, @lfades, @sokra, @AmirhBeigi, @marshalcode, @timneutkens, @mxgnus-de, @MoltenCoffee, @jonespen, @NoamNol, @khuezy, @rishabhpoddar, @kara, @reubn, @luciy, @Pauldic, @brodyd795, @eungyeole, @kyliau, @Nutlope, @jgoping, @crice88, @leerob, @SukkaW, @thibautsabot, @sincovschi, @ahollenbach, @kolarski, @AFusco, @stipsan, @sisp, @kdy1, @lydiahallie, @Skagoo, @ijjk, @klarstrup, @midgleyc, @perkinsjr, @bnoguchi, @fhinkel, @fliptheweb, @kwonoj, @leyanlo, @ericponto, @huzaifarif, @chemicalkosek, @chentsulin, @housseindjirdeh, @bernard-lin, @atcastle, @kylemh, @samsisle, @Gomurmamma, @molebox, @Xairoo, @nelodev, @SevlaMare, @lukahartwig, @losfair, @cramforce, @hiro0218, and @CommanderRoot for helping!

12.1.1#

Core Changes

12.1.1#

Core Changes

Documentation Changes

Example Changes

Misc Changes

Credits

12.1.1

12.1.1