Nuxt 4.5 Released with Experimental SSR Streaming, Vite 8, and Rspack Builder

Key Updates in Nuxt 4.5

Nuxt, the Vue-based full-stack web framework, has launched version 4.5, which includes significant build-layer upgrades and new runtime features. This release also lays groundwork for the upcoming Nuxt 5.

Major changes include the adoption of Vite 8, a rebuilt Rspack 2 builder utilizing Rsbuild, and the introduction of experimental SSR streaming.

Experimental SSR Streaming for Performance

A headline feature in Nuxt 4.5 is experimental SSR streaming, designed to improve Time to First Byte (TTFB). This is achieved by immediately flushing the HTML shell and then streaming the body as Vue renders it. It can be enabled with a single configuration flag.

Streaming is automatically disabled for bots and crawlers to ensure search engines receive fully rendered HTML. Routes using `redirect`, `cache`, `isr`, or `swr` rules will fall back to the buffered renderer. Developers are advised to test this feature carefully, as late status, header, or cookie mutations cannot reach the client once the shell is flushed, potentially affecting middleware assumptions.

Developer Tooling and Composables

Nuxt 4.5 introduces a stable error code system built on `nostics`, providing greppable codes like `NUXT_E1001` with explanations and suggested fixes. A new `useLayout` composable returns a read-only computed ref of the current route's resolved layout.

Named views now allow pages to mount multiple `<NuxtPage>` outlets using a `child@sidebar.vue` filename convention. Additionally, `useFetch` and `useAsyncData` now include a reactive `enabled` option for conditional data fetching.

Upgrade Considerations

Developers upgrading to Nuxt 4.5 should refresh their lockfiles using `nuxt upgrade --dedupe`. This is necessary due to major version bumps for `unhead` v3 and `unctx` v3, which are pulled in with this release.

An issue was reported where the new built-in `useLayout` collided with Vuetify's composable of the same name, triggering a `NUXT_B6002` warning. The Nuxt team has expressed willingness to add projects to their ecosystem tests to surface such issues before releases.