As mentioned on the forum, https://forum.builder.io/t/svelte-sdk-need-a-little-love-now-svelte-5-is-here/6904, Svelte 5 is here and taking off fast. There have been several updates already to Svelte and Sveltekit. I'm running into an issue with the Builder SDK still on Svelte 4. I also see the issue on Github: https://github.com/BuilderIO/builder/issues/3421