# Next.js v16.4.0 — Release & Upgrade Intelligence
- **Product:** Next.js (https://nextjs.org)
- **Version:** v16.4.0
- **Released:** Oct 07, 2026
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/nextjs/updates/v16.4.0/

## Executive Summary (TL;DR)
Next.js v16.4.0. Source highlight: Check out the 16.4 announcement post to get an overview of the changes.

## New Features
- feat(turbopack): support `false` values for `resolveAlias` config: #93331
- [turbopack] Add test for sideEffects with optimizePackageImports: #96549
- Turbopack: Allow DiskWatcher to use a mocked DiskFileSystem, add a small unit test: #96353
- [turbopack] Add e2e test that uses component chunks + workers: #96556
- Add a `turbopackChunking` documentation page for pages router: #96698
- docs: add authentication with Cache Components guide and iron-session example: #95802

## Improvements
- docs: improve clarity and punctuation in README: #86096
- Turbopack: improve chunk_item_content docs: #97370
- test: improve error-on-next-codemod-comment flakiness: #97553
- Improve Cache Components sync IO migration guidance: #97572
- Improve Partial Prefetching adoption checks: #97637
- perf: split cold TurboMalloc accounting paths: #97767

## Bug Fixes
- fix(scripts): correct typo in rm.mjs error message: #87015
- Fix debug build paths Pages Router support entries: #93529
- fix: detect proxy.ts correctly with compound pageExtensions: #93246
- Fix HTML-limited bot matching in prerender bypass rules: #96584
- [ci] Fix create_release_branch for new repo permissions: #96641
- [Bench] Fixes for pure Fizz bench: #96771

## Upgrade Command
```bash
npm install --save-exact next@16.4.0
```