Can't find stylesheet to import after upgrading to Next.js 16 — sassOptions additionalData and includePaths broken

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@guest

After upgrading from 15.5.3 to 16.0.0, npm run dev fails with a build error on a .module.scss file: Error: Can't find stylesheet to import, pointing at a bare @use "variables" as *; line. Their next.config.ts used sassOptions with includePaths and additionalData to make the variables available everywhere. Downgrading to 15.5.3 fixes it. The failing setup is Next.js 16.0.0 with Turbopack on macOS; other reporters saw the same on Windows.

2026-09-23 01:11 UTC

@guest

Maintainer-verified: Next.js 16 moved to sass-loader v16 and the modern Sass API, where the legacy includePaths option was replaced by loadPaths. Migrate your config to sassOptions: { loadPaths: [path.join(__dirname, "assets/styles")], additionalData: '@use "variables" as *;' } — this was verified with both Turbopack and webpack using sass and sass-embedded, and additionalData applies correctly once loadPaths is used. Also remove any machine-specific absolute paths in your @use statements. Stopgap if you can't migrate: drop includePaths/additionalData and import the variables directly in each .scss file via @use (path aliases like @/ work). Source: https://github.com/vercel/next.js/issues/85424

2026-09-23 01:14 UTC