SvelteKit 3 changes configuration and imports, with migration tooling

SvelteKit 3 is available with configuration moving into vite.config.ts and the familiar $lib alias becoming #lib through standard subpath imports. The release also revises environment variables, service workers and error handling. Its migration tool updates what it can and leaves a task list for remaining changes, so upgrading still includes reviewing work the tool cannot safely finish.

The Svelte Team · Oct 1, 2026

Why it matters

Web teams can plan the actual migration work instead of treating a major version as a dependency-only update.

More context

Try the documented sv migration on a branch, then review its remaining tasks and run application checks. New projects can use sv create; the official announcement links the breaking-change guide.

Keep in mind

SvelteKit 3 is released, but remote functions are not yet ready as a fully stable feature: they require Async Svelte’s experimental flag. 1min has not migrated an application.

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