This is fixed in 3.10.2 :)

i had the same issue but adding in my /layouts/default.vue fixed it.

app.vue

<template>
  <div>
    <NuxtLayout>
      <NuxtPage />
    </NuxtLayout>
  </div>
</template>

and <slot /> in all layouts. still having this output on nuxt 3.14.1592

This warning can also appear when you're slot is conditional.
Below reproduces this warning for me.

<SplashScreen v-if="isLoading" />
<slot v-else />

I get this warning too, because I am conditionally rendering <NuxtPage /> based on auth state. My auth server is an external auth provider (propelauth). So on page load, it takes a second to validate refresh token from the external auth server (which is not my own nitro server).

<template>
  <NuxtLoadingIndicator />
  <div v-if="auth">
    <NuxtLayout>
      <NuxtPage />
    </NuxtLayout>
  </div>
  <UContainer v-else>
    <LoginCard class="mt-24 max-w-md mx-auto" />
  </UContainer>
  <UNotifications />
</template>

<script setup lang="ts">
const auth = useAuthState();
</script>

<style scoped></style>

This was the easiest architecture for me without having to manage layouts for auth and non authed states, or managing redirects.

But as Alex mentioned, since it works as expected, I am choosing to ignore the warning for now.

I add this issue and my problem was not adding a slot to my auth layout.
Every layout should have a slot.

Yeah, for me, I just fixed it by updating nuxt module to the latest version.

I've had the same issue, this is probably because one of your layouts has a NuxtPage which is conditionally rendered

<div v-if="!pending" class="page-content"> <NuxtPage /> </div>

check app.vue and layouts/default.vue
if the app.vue and layouts/default.vue uses then try changing the one on layouts/default.vue to slot

To solve the conditional rendering issue, I used.

/layouts/default

<LoadingPage v-if="isLoading" />
<div v-show="!isLoading">
  <slot/>
</div>

I wanted to share my experience with this warning. In my layout, I centralize authentication logic: while the session is loading, I show a loader and don't render the slot; once loaded, I either redirect to login or show the slot if authenticated. Example:

<template>
  <main>
    <div v-if="session.isPending || session.isRefetching">Loading...</div>
    <slot v-else="session.data" />
  </main>
</template>
<script setup>
const session = authClient.useSession()
const { path } = useRoute()
watch(session, s => {
  if (s.isPending || s.isRefetching) return
  if (!s.data && path !== '/login') navigateTo('/login', { replace: true })
}, { immediate: true })
</script>

Using v-show on a wrapper removes the warning, but the slot’s component still executes on the server while auth is loading, so it doesn’t actually gate rendering. This means I’d need to check auth in every page, which I’m trying to avoid. Middleware solves this but delays the page and also doesn’t allow showing a loader.

I think layouts that gate rendering based on async auth are a valid use case, but current Nuxt behavior makes this tricky. I could just ignore the warning for this use case but that isn't clean.
Would appreciate any best practices or guidance!