Remote form function with data-sveltekit-preload-data="hover" setting is breaking navigation

[harishkswamy]

Describe the bug

A simple two route app with remote form functions and the data-sveltekit-preload-data set to "hover" breaks the browser hyperlink navigation between the two routes.

Reproduction

Here's StackBlitz repo https://stackblitz.com/edit/sveltejs-kit-template-default-uxxqzawj?file=src%2Froutes%2F%2Bpage.svelte

Navigate to "Login" -> "Register" -> "Login"

You will find that the URL switches to /auth/login but the page does not to refresh. If I force refresh the browser once and then use the links it seems to be working. Also, notice that this only works if I set the data-sveltekit-preload-data="off" on the links.

Logs

System Info

"@sveltejs/kit": "^2.49.1"
"svelte": "^5.45.6"
Browser: Chrome Version 143.0.7499.41 (Official Build) (arm64)

Severity

serious, but I can work around it

Additional Information

No response

[samstorment]

I've run into the same problem and I've managed to narrow the reproduction further. I don't think data-sveltekit-preload-data="hover" is the cause.

Seems like the cause is just navigating to and from a page with a remote form function spread onto a form.

I forked your StackBlitz and removed everything I could while still having the bug: https://stackblitz.com/edit/sveltejs-kit-template-default-3yofla3a?file=src%2Froutes%2F%2Bpage.svelte

I noticed the bug doesn't seem to happen if the remote form receives input or is on the first page loaded.

[harishkswamy]

Yeah it seems like it might actually have something to do with the experimental async compiler option, if I remove that option from svelte.config it seems to be fine.

[samstorment]

I started decrementing version numbers until I no longer experienced this bug. Looks like it was introduced in @sveltejs/kit@2.48.0

[erikbg7]

Using data-sveltekit-preload-data="off" in the homepage is a workaround to fix navigation:
https://stackblitz.com/edit/sveltejs-kit-template-default-nynfb8ka?file=src%2Froutes%2F%2Bpage.svelte,src%2Froutes%2Fauth%2Fregister%2F%2Bpage.svelte

This fix might completely solve it: sveltejs/svelte#17335