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

bind_invalid_checkbox_value

Using bind:value together with a checkbox input is not allowed. Use bind:checked instead

bind_invalid_export

Component %component% has an export named %key% that a consumer component is trying to access using bind:%key%, which is disallowed. Instead, use bind:this (e.g. <%name% bind:this={component} />) and then access the property on the bound component instance (e.g. component.%key%)

bind_not_bindable

A component is attempting to bind to a non-bindable property %key% belonging to %component% (i.e. <%name% bind:%key%={...}>). To mark a property as bindable: let { %key% = $bindable() } = $props()

component_api_changed

%parent% called %method% on an instance of %component%, which is no longer valid in Svelte 5. See https://svelte-5-preview.vercel.app/docs/breaking-changes#components-are-no-longer-classes for more information

component_api_invalid_new

Attempted to instantiate %component% with new %name%, which is no longer valid in Svelte 5. If this component is not under your control, set the legacy.componentApi compiler option to keep it working. See https://svelte-5-preview.vercel.app/docs/breaking-changes#components-are-no-longer-classes for more information

each_key_duplicate

Keyed each block has duplicate key at indexes %a% and %b%

Keyed each block has duplicate key %value% at indexes %a% and %b%

effect_in_teardown

%rune% cannot be used inside an effect cleanup function

effect_in_unowned_derived

Effect cannot be created inside a $derived value that was not itself created inside an effect

effect_orphan

%rune% can only be used inside an effect (e.g. during component initialisation)

effect_update_depth_exceeded

Maximum update depth exceeded. This can happen when a reactive block or effect repeatedly sets a new value. Svelte limits the number of nested updates to prevent infinite loops

hydration_failed

Failed to hydrate the application

lifecycle_legacy_only

%name%(...) cannot be used in runes mode

props_invalid_value

Cannot do bind:%key%={undefined} when %key% has a fallback value

props_rest_readonly

Rest element properties of $props() such as %property% are readonly

rune_outside_svelte

The %rune% rune is only available inside .svelte and .svelte.js/ts files

state_prototype_fixed

Cannot set prototype of $state object

state_unsafe_mutation

Updating state inside a derived is forbidden. If the value should not be reactive, declare it without $state

svelte_component_invalid_this_value

The this={...} property of a <svelte:component> must be a Svelte component, if defined