svelte/packages/svelte/messages/server-errors/errors.md

async_local_storage_unavailable

The node API AsyncLocalStorage is not available, but is required to use async server rendering.

Some platforms require configuration flags to enable this API. Consult your platform's documentation.

await_invalid

Encountered asynchronous work while rendering synchronously.

You (or the framework you're using) called render(...) with a component containing an await expression. Either await the result of render or wrap the await (or the component containing it) in a <svelte:boundary> with a pending snippet.

html_deprecated

The html property of server render results has been deprecated. Use body instead.

hydratable_clobbering

Attempted to set hydratable with key %key% twice with different values.

%stack%

This error occurs when using hydratable multiple times with the same key. To avoid this, you can:

• Ensure all invocations with the same key result in the same value
• Update the keys to make both instances unique

<script>
  import { hydratable } from 'svelte';

  // which one should "win" and be serialized in the rendered response?
  const one = hydratable('not-unique', () => 1);
  const two = hydratable('not-unique', () => 2);
</script>

hydratable_serialization_failed

Failed to serialize hydratable data for key %key%.

hydratable can serialize anything uneval from devalue can, plus Promises.

Cause: %stack%

lifecycle_function_unavailable

%name%(...) is not available on the server

Certain methods such as mount cannot be invoked while running in a server context. Avoid calling them eagerly, i.e. not during render.

server_context_required

Could not resolve render context.

Certain functions such as hydratable cannot be invoked outside of a render(...) call, such as at the top level of a module.