# Next.js v15.5.0 — Release & Upgrade Intelligence
- **Product:** Next.js (https://nextjs.org)
- **Version:** v15.5.0
- **Released:** Aug 20, 2025
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/nextjs/updates/v15.5.0/

## Executive Summary (TL;DR)
Next.js v15.5.0. Source highlight: Use and enforce exhaustive switch statements for work unit store: #81577

## New Features
- feat: new detachable panel UI: #81483
- Also enforce experimental features when there's no next config file: #81679
- feat(next/image): warn when `images.qualities` is undefined: #81690
- feat(build): optimize filterUniqueParamsCombinations to generate sub-combinations: #81321
- perf(build): optimize buildAppStaticPaths performance and add helper function: #81386
- feat(turbopack): Log anonymized internal error (panic) information to telemetry: #81272

## Improvements
- Improve reliability of owner stacks for async I/O errors: #81501
- perf: memorize exclude function in webpack config: #81525
- Improve error handling for `headers`/`cookies`/`draftMode` in `'use cache'`: #81716
- [perf] cache load config results: #80570
- Turbopack: use prototype for turbopack context for better runtime performance: #81547
- perf(router): replace LRU cache with optimized doubly-linked list implementation: #82633

## Bug Fixes
- [segment explorer] fix content overflow styling: #81649
- fix(router): Prevent redirect loop on root data requests with basePath: #81096
- Fix before interactive incorrectly render css: #81146
- fix: rootParams should throw in client when fallbackParams are not present: #81711
- fix: revert client segment route changes for sub shell generation: #81731
- fix: pages router metadata bugs with React 19: #81733

## Upgrade Command
```bash
npm install --save-exact next@15.5.0
```