<Routes> received an unexpected slot "default".

[vfilatov]

Describe the bug
Recently appeared in a dev tool three warnings.

Logs
received an unexpected slot "default". index.mjs?v=76284753:1656
was created with unknown prop 'status' index.svelte:2
was created with unknown prop 'error' index.svelte:2

To Reproduce
npm init svelte@next
npm install
npm run dev
in browser, open dev tool and navigate to http://localhost:3000

[vfilatov]

looks fixed in "SvelteKit v1.0.0-next.74"

[vfilatov]

I was wrong, it still throws a warning.
<Routes> received an unexpected slot "default".

[Rich-Harris]

People, you don't need to comment saying that the warning is still there. As long as the issue remains open you can assume it's still there — that's how issues work :)

[pngwn]

It is just a dev-time warning, none of these show up in the production build.

[jakobrosenberg]

Could this issue be addressed at Svelte level? For package creators it would be nice to be to able to tell Svelte to filter harmless warnings produced by the package.

Something like

window.__svelteMsgFilter = msg => msg !== 'ignore me'

[Rich-Harris]

I think it'll have to be addressed at a Svelte level somehow, yeah

[PuruVJ]

I'm having this warning when routing to other pages, just like your case. However, If I navigate to a page whose path isn't / (/blog or /works), it shows the $error page instead.

Something might have gone wrong moving from Sapper to Sveltekit 😔 https://github.com/puruvj/puruvjdev3-svelte

Anyone else facing the same issue?

[ebeloded]

Is this issue being tracked in Svelte repository? I am finding PRs addressing similarly sounding issues being merged and issues closed.

[bluebrown]

so, not a big deal, of course, as nothing breaks in development and they don't show up in production...just...you know...the warnings do add up and pollute the console quite a bit :-)

It is refreshing the browser page, not just polluting the logs. It makes literally a new network request to get resources each time it throws that warning.

[LLIETAER]

I notice is you add the "slot" tags in your pages it suppress the log. I seems logical as somehow a default slot content is provided to pages.

[M1sf3t]

That warning has been showing up since I first started using sapper two years ago, no idea what causes it but it's yet to cause an actual issue

[AshishKapoor]

So the default slot inside __layout needs to be named? The warning isn't showing up in production build though.

[rchrdnsh]

I think it's much more involved than that, as I get a warning for every exported prop on every page all the time always. I will have hundreds upon hundreds of these warnings when in development...it's no fun, to be sure, but as you say, they do not show up in production...dunno at this point if this is a bug or a feature...maybe a little Stockholm Syndrome? 🤪

[basaran]

Has anyone found a solution to this issue? I tried naming the slot in __layout file, but I'm not sure how to use it in the page.

<div slot="pika">
    <h3>Welcome to Carbon</h3>
    <p>
        Visit <a href="https://kit.svelte.dev">kit.svelte.dev</a>
        to read the documentation.
    </p>
</div>

is coming back with a nicely formatted:

Element with a slot='...' attribute must be a child of a component or a descendant of a custom element

[fourglobe302500]

This issue is happening to me in another way. I just created a new project via npm init svelte@next <app-name> and created a __layout.svelt file. But the layout does not render and the only thing that shows any sign of error is this <Routes> received an unexpected slot "default".

[ibilux]

This seem to do the trick for now!
{#if false}<slot/>{/if}

For some unknown reason the components are receiving an unexpected slot "default" (unnamed slot), while the component don't have a default slot <slot/>.

[benmccann]

Closing this in favor of the issue in the Svelte repo since that's where this would need to be solved sveltejs/svelte#6325

[CJ13th]

This issue is happening to me in another way. I just created a new project via npm init svelte@next <app-name> and created a __layout.svelt file. But the layout does not render and the only thing that shows any sign of error is this <Routes> received an unexpected slot "default".

Check which version of Svelte you are running, I was running 3.44.0 but after I updated to 3.44.3 the issued resolved itself.

[moritzlaube]

Does anyone know the reason why this is happening? I issued a pull request for astros svelte renderer to update to the latest svelte version 3.44.3 but the issue persists. It's not a deal breaker. It's only annoying when you get the same warning for every svelte-component you use. Cheers!

[kylesloper]

Does anyone know the reason why this is happening? I issued a pull request for astros svelte renderer to update to the latest svelte version 3.44.3 but the issue persists. It's not a deal breaker. It's only annoying when you get the same warning for every svelte-component you use. Cheers!

Glad it's not just me seeing this in Astro then. Have you found a way to deal with it?

[moritzlaube]

Unfortunately, I haven't …

[divStar]

Weird.. using Svelte (not SvelteKit) and Routify (V3), I also get these warnings and their variations at _module.svelte-level.

<Module> was created with unknown prop 'context' [_module.svelte:163:92](http://localhost:5173/src/routes/_module.svelte?t=1663453395158)
<Noop> was created with unknown prop 'date' [Noop.svelte:86:92](http://localhost:5173/node_modules/@roxi/routify/lib/runtime/decorators/Noop.svelte?v=d4cd57d8)
<U5Bdateu5D> received an unexpected slot "default". [index.mjs:2084:20](http://localhost:5173/node_modules/svelte/internal/index.mjs)
<U5Bdateu5D> was created with unknown prop 'context' [index.svelte:465:92](http://localhost:5173/src/routes/calendar/[date]/index.svelte?t=1663453239282)

No clue what's causing them...

[jakobrosenberg]

@divStar it's Svelte that generates these, not Kit. They occur when you pass a prop to a component, but the component doesn't have a corresponding export let <prop>. In your case R3 passes a context prop to the component.