# What changed in svelte-preprocess

> 7 changes in svelte-preprocess 5 to 6 from its official release notes, upgrade guides and advisories: 3 breaking. Each one cited. Sources checked 2026-10-27. HTML: https://unstale.sh/npm/svelte-preprocess/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## svelte-preprocess 6

### Fixes and other changes

- Correctly imports the transformer when automatically processing with TypeScript 6. (6.0.5) — [release notes](https://github.com/sveltejs/svelte-preprocess/releases/tag/svelte-preprocess%406.0.5)
- Adds support for TypeScript 6. (6.0.4) — [release notes](https://github.com/sveltejs/svelte-preprocess/releases/tag/svelte-preprocess%406.0.4)

## svelte-preprocess 5

### Breaking changes

- Languages must be explicitly defined via the lang attribute; the type attribute can no longer identify a style or script language. (5.0.0) — [release notes](https://github.com/sveltejs/svelte-preprocess/blob/HEAD/CHANGELOG.md)
- The minimum Node version is now 14, increased from 9. (5.0.0) — [release notes](https://github.com/sveltejs/svelte-preprocess/blob/HEAD/CHANGELOG.md)
- node-sass is no longer supported; use sass instead. (5.0.0) — [release notes](https://github.com/sveltejs/svelte-preprocess/blob/HEAD/CHANGELOG.md)

### Fixes and other changes

- The .sss extension is mapped as .css to support the SugarSS extension. (5.0.0) — [release notes](https://github.com/sveltejs/svelte-preprocess/blob/HEAD/CHANGELOG.md)
- SugarSS versions 3 and 4 are supported. (5.0.0) — [release notes](https://github.com/sveltejs/svelte-preprocess/blob/HEAD/CHANGELOG.md)