svelte/documentation/docs/98-reference/30-compiler-errors.md

title	generated
Compiler errors	generated by process-messages/index.js

animation_duplicate

[!NOTE] An element can only have one 'animate' directive

animation_invalid_placement

[!NOTE] An element that uses the 'animate:' directive must be the only child of a keyed '{#each ...}' block

animation_missing_key

[!NOTE] An element that uses the 'animate:' directive must be the only child of a keyed '{#each ...}' block. Did you forget to add a key to your each block?

attribute_contenteditable_dynamic

[!NOTE] 'contenteditable' attribute cannot be dynamic if element uses two-way binding

attribute_contenteditable_missing

[!NOTE] 'contenteditable' attribute is required for textContent, innerHTML and innerText two-way bindings

attribute_duplicate

[!NOTE] Attributes need to be unique

attribute_empty_shorthand

[!NOTE] Attribute shorthand cannot be empty

attribute_invalid_event_handler

[!NOTE] Event attribute must be a JavaScript expression, not a string

attribute_invalid_multiple

[!NOTE] 'multiple' attribute must be static if select uses two-way binding

attribute_invalid_name

[!NOTE] '%name%' is not a valid attribute name

attribute_invalid_sequence_expression

[!NOTE] Sequence expressions are not allowed as attribute/directive values in runes mode, unless wrapped in parentheses

attribute_invalid_type

[!NOTE] 'type' attribute must be a static text value if input uses two-way binding

attribute_unquoted_sequence

[!NOTE] Attribute values containing '{...}' must be enclosed in quote marks, unless the value only contains the expression

bind_invalid_expression

[!NOTE] Can only bind to an Identifier or MemberExpression

bind_invalid_name

[!NOTE] 'bind:%name%' is not a valid binding

[!NOTE] 'bind:%name%' is not a valid binding. %explanation%

bind_invalid_target

[!NOTE] 'bind:%name%' can only be used with %elements%

bind_invalid_value

[!NOTE] Can only bind to state or props

bindable_invalid_location

[!NOTE] '$bindable()' can only be used inside a '$props()' declaration

block_duplicate_clause

[!NOTE] %name% cannot appear more than once within a block

block_invalid_continuation_placement

[!NOTE] {:...} block is invalid at this position (did you forget to close the preceeding element or block?)

block_invalid_elseif

[!NOTE] 'elseif' should be 'else if'

block_invalid_placement

[!NOTE] {#%name% ...} block cannot be %location%

block_unclosed

[!NOTE] Block was left open

block_unexpected_character

[!NOTE] Expected a '%character%' character immediately following the opening bracket

block_unexpected_close

[!NOTE] Unexpected block closing tag

component_invalid_directive

[!NOTE] This type of directive is not valid on components

const_tag_cycle

[!NOTE] Cyclical dependency detected: %cycle%

const_tag_invalid_expression

[!NOTE] {@const ...} must consist of a single variable declaration

const_tag_invalid_placement

[!NOTE] '{@const}' must be the immediate child of '{#snippet}', '{#if}', '{:else if}', '{:else}', '{#each}', '{:then}', '{:catch}', '<svelte:fragment>' or '<Component>'

constant_assignment

[!NOTE] Cannot assign to %thing%

constant_binding

[!NOTE] Cannot bind to %thing%

css_empty_declaration

[!NOTE] Declaration cannot be empty

css_expected_identifier

[!NOTE] Expected a valid CSS identifier

css_global_block_invalid_combinator

[!NOTE] A ':global' selector cannot follow a '%name%' combinator

css_global_block_invalid_declaration

[!NOTE] A top-level ':global {...}' block can only contain rules, not declarations

css_global_block_invalid_list

[!NOTE] A ':global' selector cannot be part of a selector list with more than one item

css_global_block_invalid_modifier

[!NOTE] A ':global' selector cannot modify an existing selector

css_global_block_invalid_modifier_start

[!NOTE] A ':global' selector can only be modified if it is a descendant of other selectors

css_global_invalid_placement

[!NOTE] ':global(...)' can be at the start or end of a selector sequence, but not in the middle

css_global_invalid_selector

[!NOTE] ':global(...)' must contain exactly one selector

css_global_invalid_selector_list

[!NOTE] ':global(...)' must not contain type or universal selectors when used in a compound selector

css_nesting_selector_invalid_placement

[!NOTE] Nesting selectors can only be used inside a rule or as the first selector inside a lone ':global(...)'

css_selector_invalid

[!NOTE] Invalid selector

css_type_selector_invalid_placement

[!NOTE] ':global(...)' must not be followed by a type selector

debug_tag_invalid_arguments

[!NOTE] {@debug ...} arguments must be identifiers, not arbitrary expressions

declaration_duplicate

[!NOTE] '%name%' has already been declared

declaration_duplicate_module_import

[!NOTE] Cannot declare a variable with the same name as an import inside '<script module>'

derived_invalid_export

[!NOTE] Cannot export derived state from a module. To expose the current derived value, export a function returning its value

directive_invalid_value

[!NOTE] Directive value must be a JavaScript expression enclosed in curly braces

directive_missing_name

[!NOTE] '%type%' name cannot be empty

dollar_binding_invalid

[!NOTE] The $ name is reserved, and cannot be used for variables and imports

dollar_prefix_invalid

[!NOTE] The $ prefix is reserved, and cannot be used for variables and imports

each_item_invalid_assignment

[!NOTE] Cannot reassign or bind to each block argument in runes mode. Use the array and index variables instead (e.g. 'array[i] = value' instead of 'entry = value')

effect_invalid_placement

[!NOTE] '$effect()' can only be used as an expression statement

element_invalid_closing_tag

[!NOTE] '</%name%>' attempted to close an element that was not open

element_invalid_closing_tag_autoclosed

[!NOTE] '</%name%>' attempted to close element that was already automatically closed by '<%reason%>' (cannot nest '<%reason%>' inside '<%name%>')

element_unclosed

[!NOTE] '<%name%>' was left open

event_handler_invalid_component_modifier

[!NOTE] Event modifiers other than 'once' can only be used on DOM elements

event_handler_invalid_modifier

[!NOTE] Valid event modifiers are %list%

event_handler_invalid_modifier_combination

[!NOTE] The '%modifier1%' and '%modifier2%' modifiers cannot be used together

expected_attribute_value

[!NOTE] Expected attribute value

expected_block_type

[!NOTE] Expected 'if', 'each', 'await', 'key' or 'snippet'

expected_identifier

[!NOTE] Expected an identifier

expected_pattern

[!NOTE] Expected identifier or destructure pattern

expected_token

[!NOTE] Expected token %token%

expected_whitespace

[!NOTE] Expected whitespace

global_reference_invalid

[!NOTE] '%name%' is an illegal variable name. To reference a global variable called '%name%', use 'globalThis.%name%'

host_invalid_placement

[!NOTE] '$host()' can only be used inside custom element component instances

import_svelte_internal_forbidden

[!NOTE] Imports of 'svelte/internal/*' are forbidden. It contains private runtime code which is subject to change without notice. If you're importing from 'svelte/internal/*' to work around a limitation of Svelte, please open an issue at https://github.com/sveltejs/svelte and explain your use case

invalid_arguments_usage

[!NOTE] The arguments keyword cannot be used within the template or at the top level of a component

js_parse_error

[!NOTE] %message%

legacy_export_invalid

[!NOTE] Cannot use 'export let' in runes mode — use '$props()' instead

legacy_props_invalid

[!NOTE] Cannot use '$$props' in runes mode

legacy_reactive_statement_invalid

[!NOTE] '$:' is not allowed in runes mode, use '$derived' or '$effect' instead

legacy_rest_props_invalid

[!NOTE] Cannot use '$$restProps' in runes mode

let_directive_invalid_placement

[!NOTE] 'let:' directive at invalid position

mixed_event_handler_syntaxes

[!NOTE] Mixing old (on:%name%) and new syntaxes for event handling is not allowed. Use only the on%name% syntax

module_illegal_default_export

[!NOTE] A component cannot have a default export

node_invalid_placement

[!NOTE] %thing% is invalid inside '<%parent%>'

HTML restricts where certain elements can appear. In case of a violation the browser will 'repair' the HTML in a way that breaks Svelte's assumptions about the structure of your components. Some examples:

• <p>hello <div>world</div></p> will result in <p>hello </p><div>world</div><p></p> for example (the <div> autoclosed the <p> because <p> cannot contain block-level elements)
• <option><div>option a</div></option> will result in <option>option a</option> (the <div> is removed)
• <table><tr><td>cell</td></tr></table> will result in <table><tbody><tr><td>cell</td></tr></tbody></table> (a <tbody> is auto-inserted)

options_invalid_value

[!NOTE] Invalid compiler option: %details%

options_removed

[!NOTE] Invalid compiler option: %details%

options_unrecognised

[!NOTE] Unrecognised compiler option %keypath%

props_duplicate

[!NOTE] Cannot use '$props()' more than once

props_illegal_name

[!NOTE] Declaring or accessing a prop starting with '' is illegal (they are reserved for Svelte internals)

props_invalid_identifier

[!NOTE] '$props()' can only be used with an object destructuring pattern

props_invalid_pattern

[!NOTE] '$props()' assignment must not contain nested properties or computed keys

props_invalid_placement

[!NOTE] '$props()' can only be used at the top level of components as a variable declaration initializer

reactive_declaration_cycle

[!NOTE] Cyclical dependency detected: %cycle%

render_tag_invalid_call_expression

[!NOTE] Calling a snippet function using apply, bind or call is not allowed

render_tag_invalid_expression

[!NOTE] '{@render ...}' tags can only contain call expressions

render_tag_invalid_spread_argument

[!NOTE] cannot use spread arguments in '{@render ...}' tags

rune_invalid_arguments

[!NOTE] '%rune%' cannot be called with arguments

rune_invalid_arguments_length

[!NOTE] '%rune%' must be called with %args%

rune_invalid_computed_property

[!NOTE] Cannot access a computed property of a rune

rune_invalid_name

[!NOTE] '%name%' is not a valid rune

rune_invalid_usage

[!NOTE] Cannot use '%rune%' rune in non-runes mode

rune_missing_parentheses

[!NOTE] Cannot use rune without parentheses

rune_removed

[!NOTE] The '%name%' rune has been removed

rune_renamed

[!NOTE] '%name%' is now '%replacement%'

runes_mode_invalid_import

[!NOTE] %name% cannot be used in runes mode

script_duplicate

[!NOTE] A component can have a single top-level '<script>' element and/or a single top-level '<script module>' element

script_invalid_attribute_value

[!NOTE] If the '%name%' attribute is supplied, it must be a boolean attribute

script_invalid_context

[!NOTE] If the context attribute is supplied, its value must be "module"

script_reserved_attribute

[!NOTE] The '%name%' attribute is reserved and cannot be used

slot_attribute_duplicate

[!NOTE] Duplicate slot name '%name%' in <%component%>

slot_attribute_invalid

[!NOTE] slot attribute must be a static value

slot_attribute_invalid_placement

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

slot_default_duplicate

[!NOTE] Found default slot content alongside an explicit slot="default"

slot_element_invalid_attribute

[!NOTE] '<slot>' can only receive attributes and (optionally) let directives

slot_element_invalid_name

[!NOTE] slot attribute must be a static value

slot_element_invalid_name_default

[!NOTE] 'default' is a reserved word — it cannot be used as a slot name

slot_snippet_conflict

[!NOTE] Cannot use '<slot>' syntax and '{@render ...}' tags in the same component. Migrate towards '{@render ...}' tags completely

snippet_conflict

[!NOTE] Cannot use explicit children snippet at the same time as implicit children content. Remove either the non-whitespace content or the children snippet block

snippet_invalid_rest_parameter

[!NOTE] Snippets do not support rest parameters; use an array instead

snippet_parameter_assignment

[!NOTE] Cannot reassign or bind to snippet parameter

snippet_shadowing_prop

[!NOTE] This snippet is shadowing the prop '%prop%' with the same name

state_invalid_export

[!NOTE] Cannot export state from a module if it is reassigned. Either export a function returning the state value or only mutate the state value's properties

state_invalid_placement

[!NOTE] '%rune%(...)' can only be used as a variable declaration initializer or a class field

store_invalid_scoped_subscription

[!NOTE] Cannot subscribe to stores that are not declared at the top level of the component

store_invalid_subscription

[!NOTE] Cannot reference store value inside '<script module>'

store_invalid_subscription_module

[!NOTE] Cannot reference store value outside a '.svelte' file

Using a $ prefix to refer to the value of a store is only possible inside .svelte files, where Svelte can automatically create subscriptions when a component is mounted and unsubscribe when the component is unmounted. Consider migrating to runes instead.

style_directive_invalid_modifier

[!NOTE] 'style:' directive can only use the 'important' modifier

style_duplicate

[!NOTE] A component can have a single top-level '<style>' element

svelte_body_illegal_attribute

[!NOTE] '<svelte:body>' does not support non-event attributes or spread attributes

svelte_component_invalid_this

[!NOTE] Invalid component definition — must be an '{expression}'

svelte_component_missing_this

[!NOTE] '<svelte:component>' must have a 'this' attribute

svelte_element_missing_this

[!NOTE] '<svelte:element>' must have a 'this' attribute with a value

svelte_fragment_invalid_attribute

[!NOTE] '<svelte:fragment>' can only have a slot attribute and (optionally) a let: directive

svelte_fragment_invalid_placement

[!NOTE] '<svelte:fragment>' must be the direct child of a component

svelte_head_illegal_attribute

[!NOTE] '<svelte:head>' cannot have attributes nor directives

svelte_meta_duplicate

[!NOTE] A component can only have one '<%name%>' element

svelte_meta_invalid_content

[!NOTE] <%name%> cannot have children

svelte_meta_invalid_placement

[!NOTE] '<%name%>' tags cannot be inside elements or blocks

svelte_meta_invalid_tag

[!NOTE] Valid '<svelte:...>' tag names are %list%

svelte_options_deprecated_tag

[!NOTE] "tag" option is deprecated — use "customElement" instead

svelte_options_invalid_attribute

[!NOTE] '<svelte:options>' can only receive static attributes

svelte_options_invalid_attribute_value

[!NOTE] Value must be %list%, if specified

svelte_options_invalid_customelement

[!NOTE] "customElement" must be a string literal defining a valid custom element name or an object of the form { tag?: string; shadow?: "open" | "none"; props?: { [key: string]: { attribute?: string; reflect?: boolean; type: .. } } }

svelte_options_invalid_customelement_props

[!NOTE] "props" must be a statically analyzable object literal of the form "{ [key: string]: { attribute?: string; reflect?: boolean; type?: "String" | "Boolean" | "Number" | "Array" | "Object" }"

svelte_options_invalid_customelement_shadow

[!NOTE] "shadow" must be either "open" or "none"

svelte_options_invalid_tagname

[!NOTE] Tag name must be lowercase and hyphenated

See https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name for more information on valid tag names

svelte_options_reserved_tagname

[!NOTE] Tag name is reserved

See https://html.spec.whatwg.org/multipage/custom-elements.html#valid-custom-element-name for more information on valid tag names

svelte_options_unknown_attribute

[!NOTE] '<svelte:options>' unknown attribute '%name%'

svelte_self_invalid_placement

[!NOTE] '<svelte:self>' components can only exist inside '{#if}' blocks, '{#each}' blocks, '{#snippet}' blocks or slots passed to components

tag_invalid_name

[!NOTE] Expected a valid element or component name. Components must have a valid variable name or dot notation expression

tag_invalid_placement

[!NOTE] {@%name% ...} tag cannot be %location%

textarea_invalid_content

[!NOTE] A '<textarea>' can have either a value attribute or (equivalently) child content, but not both

title_illegal_attribute

[!NOTE] '<title>' cannot have attributes nor directives

title_invalid_content

[!NOTE] '<title>' can only contain text and {tags}

transition_conflict

[!NOTE] Cannot use '%type%:' alongside existing '%existing%:' directive

transition_duplicate

[!NOTE] Cannot use multiple '%type%:' directives on a single element

typescript_invalid_feature

[!NOTE] TypeScript language features like %feature% are not natively supported, and their use is generally discouraged. Outside of '<script>' tags, these features are not supported. For use within '<script>' tags, you will need to use a preprocessor to convert it to JavaScript before it gets passed to the Svelte compiler. If you are using 'vitePreprocess', make sure to specifically enable preprocessing script tags ('vitePreprocess({ script: true })')

unexpected_eof

[!NOTE] Unexpected end of input

unexpected_reserved_word

[!NOTE] '%word%' is a reserved word in JavaScript and cannot be used here

void_element_invalid_content

[!NOTE] Void elements cannot have children or closing tags