TL;DR

SvelteKit now supports configuring it directly through Vite plugins, offering greater flexibility for advanced users.

Fixes Worth Knowing

• Fixed an issue where multiple Set-Cookie headers were lost on 304 (not modified) responses, which could affect session management.
• Improved preloading behavior for anchor tags, ensuring resources are loaded correctly when navigating back.
• Client-side errors during data loading are now handled more gracefully, preventing crashes.
• Apps no longer generate an unnecessary environment file if dynamic environment variables aren’t used.

TL;DR

SvelteKit now fully supports Vite v5, improving performance and developer experience with the latest build tool.

New

• Enhanced image component now supports the latest Vite plugin version, ensuring compatibility and access to new features.

Fixes Worth Knowing

• Resolved an issue where images would not load correctly in certain Vite configurations.

TL;DR

SvelteKit applications now benefit from updated tooling, improving build performance and dependency security through Rollup 4.59.0 (a JavaScript module bundler).

Fixes Worth Knowing

• Updated dependencies resolve potential security vulnerabilities and improve overall stability.

TL;DR

SvelteKit now correctly handles remote function requests and unknown routes when using Netlify’s split functions, improving the reliability of dynamic content.

Fixes Worth Knowing

• Netlify adapter: Correctly matches URL parameters, resolving issues with route handling.
• Vercel adapter: Prevents unnecessary system files from being copied during builds, reducing deployment size.
• Vercel adapter: Fixes 404 errors for immutable assets (static files) that weren’t being served correctly.

TL;DR

SvelteKit now supports updated versions of its adapters, including Netlify 6, improving deployment compatibility and functionality.

Fixes Worth Knowing

Redirects and _routes.json (routing definitions) are now handled more reliably, resolving issues with comment lines in _redirects and preventing errors when _routes.json is incorrectly placed in the static directory.

TL;DR

SvelteKit static site adapters now correctly handle homepage definitions, ensuring links work as expected when deployed.

Breaking

• The adapter-static adapter now requires a correctly formatted "homepage" field in package.json (project metadata).

Fixes Worth Knowing

• Fixed an issue where links wouldn’t resolve correctly on static sites (websites served as HTML files) due to incorrect homepage configuration.

Before You Upgrade

• Verify your package.json file includes a valid "homepage" field pointing to your deployed site’s base URL.

TL;DR

SvelteKit now supports AMP (Accelerated Mobile Pages) components, enabling faster loading and improved SEO for mobile content.

New

• Added support for AMP components via @sveltejs/amp allowing creation of optimized mobile pages.

Fixes Worth Knowing

• No user-facing fixes in this release.

Before You Upgrade

• No specific upgrade steps are needed.

TL;DR

SvelteKit now correctly handles deployments on Windows machines when using the Netlify adapter.

Fixes Worth Knowing

• Fixed an issue preventing successful builds on Windows (operating system).

Before You Upgrade

• No action needed.

TL;DR

SvelteKit has been upgraded to Vite 4 and Svelte 3.54.0, requiring updates to your project’s dependencies and potentially your build configuration.

Breaking

• Vite 4 Upgrade: Requires updating your Vite configuration and potentially resolving compatibility issues with Vite plugins.
• Svelte Dependency: Update your project to use Svelte version 3.54.0 or higher.
• invalid()/ValidationError: invalid() has been renamed to fail() and ValidationError to ActionFailure.
• Fallback Generation: Automatic fallback generation is removed; use builder.generateFallback(fallback) instead.
• sveltekit() Return: The sveltekit() function now returns a promise of an array of Vite plugins.
• __data.json Stripping: The __data.json suffix is now stripped from URLs.
• Invalid Load Responses: Errors are now thrown on invalid load responses.
• Unknown Exports: Disallows unknown exports from server files (except those starting with an underscore).

New

• vitePreprocess: