Next.js 16 makes Turbopack the default. Migration is mostly free.

Next.js 16 has been out since October 2025, and the migration story is now clearer than it was at launch [Next.js 16 release].

── What shipped ──

Turbopack is the default bundler for both next dev and next build. Vercel cites 5–10x faster Fast Refresh and 2–5x faster production builds for typical projects [Next.js 16 release].

Three changes that matter for migration:

• middleware.ts → proxy.ts. The file is renamed to clarify the network boundary. Behaviour is identical; the rename is mechanical.
• Cache Components. A new caching primitive built on Partial Pre-Rendering and use cache directives. The previous segment-level revalidate API still works but is no longer the recommended approach.
• Build Adapters API. Hosting providers (Cloudflare, Netlify, AWS, etc.) get a stable hook to mutate config and post-process build output. This unblocks first-class non-Vercel deployments [InfoQ].

── Why it matters ──

Turbopack moving to default is the visible change. The under-discussed change is the Build Adapters API — it removes a long-standing complaint that Next.js was easy on Vercel and awkward everywhere else. With a public adapter API, expect first-class adapters from Cloudflare, AWS Lambda, and self-hosted Node within the next two release cycles.

For teams sitting on Next.js 14 or 15: the upgrade path is mostly mechanical. Rename middleware.ts to proxy.ts, update Node 20 → 22 if needed, and run the codemods. Cache Components is opt-in — old caching keeps working.

The webpack-to-Turbopack delta is the place to measure. If you have custom webpack config (image loaders, transformers, plugin chains), check whether Turbopack supports your specific chain — this is where most reported migration friction sits.

── Editor's take ──

Six months of community shake-out has done the de-risking work. If you are running Next.js 14 or 15 in production today, schedule a one-engineer-week migration window in the next quarter. The performance gain pays the cost back.