Checks reference

You can run the following checks as part of Theme Check. Each check identifies a specific error or a place in your code where a best practice is not being followed.

To learn more about the check and its options, click on the name of the check.

Anchor to Liquid file checksLiquid file checks

These checks analyze the style and validity of Liquid code. Some of these checks support auto-correction using the --auto-correct flag.

Check	Severity	Purpose	Auto-correction
AppBlockValidTags	Error	Identifies forbidden Liquid tags in theme app extension app block and app embed block code.
AssetPreload	Warning	Encourages preloading of assets using Liquid filters, rather than HTML attributes.
AssetSizeAppBlockCSS	Error	Prevents theme app extensions from using CSS files larger than the configured threshold.
AssetSizeAppBlockJavascript	Error	Prevents theme app extensions from using JavaScript files and external scripts with a compressed size larger than the configured threshold.
AssetSizeCSS	Error	Prevents themes from using CSS files larger than the configured threshold.
AssetSizeJavaScript	Error	Prevents using theme JavaScript files and external scripts with a compressed size greater than the configured threshold.
BlockIdUsage	Warning	Warns against the use of block IDs in conditional statements and case statements.
CdnPreconnect	Warning	This check is aimed at signaling the redundant preconnect to Shopify's CDN.
ContentForHeaderModification	Error	Identifies code that tries to parse `content_for_header` .
DeprecateBgsizes	Warning	Discourages use of the bgset extension instead of the image-set attribute for loading background images.
DeprecateLazysizes	Warning	Discourages use of the lazysizes library for lazy loading images, iframes, and scripts.
DeprecatedFilter	Warning	Discourages using deprecated filters in themes.	Yes
DeprecatedFontsOnSectionsAndBlocks	Warning	Discourages using deprecated fonts in section and block schemas.
DeprecatedFontsOnSettingsSchema	Warning	Discourages using deprecated fonts in the `settings_schema.json` file.
DeprecatedTag	Error	Discourages using deprecated tags in themes.
DuplicateContentForArguments	Warning	Identifies when argument names provided for the `content_for` tag are not unique.
DuplicateRenderSnippetArguments	Warning	Identifies when argument names provided for the `render` tag are not unique.
EmptyBlockContent	Warning	Detects instances where the Liquid tag `{% content_for 'blocks' %}` is used when the associated schema `blocks` array is empty or undefined.
HardcodedRoutes	Warning	Encourages use of the routes object instead of hardcoding URLs.
ImgWidthAndHeight	Error	Enforces setting the `width` and `height` attributes on `img` tags.
LiquidFreeSettings	Warning	Identifies when a theme is using the `{% liquid %}` tag within `Settings` values.
LiquidHTMLSyntaxError	Error	Identifies Liquid and HTML syntax errors.
MissingAsset	Error	Makes sure that all asset files referenced by the `asset_url` filter exist.
AppBlockMissingSchema	Error	Ensures schema is present in app blocks in theme app extensions.
MissingContentForArguments	Warning	Identifies when required arguments are not provided when using a `content_for` tag.
MissingRenderSnippetArguments	Warning	Identifies when required arguments are not provided when using a `render` tag.
MissingTemplate	Warning	Identifies when a resource is referenced using a `render` , `section` , or `include` tag, but doesn't exist.	Yes
PaginationSize	Warning	Ensures that objects are paginated with performant sizes so too many objects are not loaded at once.
ParserBlockingJavaScript	Error	Identifies script tags that don't have defer or async attributes, avoiding parser-blocking JavaScript.
RemoteAsset	Warning	Discourages use of third party domains for hosting assets.
RequiredLayoutThemeObject	Error	Makes sure that the theme.liquid layout file contains the required `{{ content_for_header }}` and `{{ content_for_layout }}` objects.	Yes
SchemaPresetsBlockOrder	Warning	Makes sure that the section and block schema presets are correctly used in the `block_order`.
SchemaPresetsStaticBlocks	Error	Warns if a preset static block doesn't have a `{% content_for "block" ... %}` tag in the Liquid code.
StaticStylesheetAndJavascriptTags	Error	Warns if Liquid code is used inside a `{% stylesheet %}` or `{% javascript %}` tag.
TranslationKeyExists	Error	Identifies references to translations that don't exist.
UnclosedHTMLElement	Error	Identifies instances of unclosed HTML elements in branching code.
UndefinedObject	Error	Identifies references to undefined Liquid objects.
UniqueStaticBlockId	Error	Identifies when two static blocks are using the same ID.
UnknownFilter	Error	Identifies references to unknown Liquid filters.
UnusedAssign	Warning	Identifies variable definitions that aren't used.
UniqueDocParamNames	Error	Identifies when parameter names in LiquidDoc are not unique.
UnrecognizedContentForArguments	Warning	Identifies when unknown arguments for a static block are provided when using a `content_for` tag.
UnrecognizedRenderSnippetArguments	Warning	Identifies when unknown arguments for a snippet are provided when using a `render` tag.
UnsupportedDocTag	Error	Identifies when LiquidDoc tag is used outside of snippets.
UnusedDocParam	Warning	Identifies when parameters are defined within LiquidDoc, but are not used within the snippet.
ValidBlockTarget	Error	Identifies when a block is using an invalid target.
ValidContentForArguments	Error	Identifies invalid arguments passed to the `{% content_for %}` tag
ValidContentForArgumentTypes	Warning	Identifies when arguments are provided when using a `content_for` tag, but the types of the arguments don't match the type defined in the block's LiquidDoc.
ValidDocParamNames	Warning	Identifies when parameter names within LiquidDoc collide with reserved liquid keywords.
ValidDocParamTypes	Error	Identifies when invalid parameter types exist in LiquidDoc.
ValidLocalBlocks	Error	Identifies when a local block is used incorrectly.
ValidRenderSnippetArgumentTypes	Warning	Identifies when arguments are provided when using a `render` tag, but the types of the arguments don't match the type defined in the snippet's LiquidDoc.
ValidSchema	Warning	Identifies invalid JSON in `{% schema %}` tags.
ValidSchemaName	Error	Identifies invalid values for the schema name property.
ValidSettingsKey	Error	Identifies when preset settings key, default settings key, or referenced block setting key is defined in their respective schema.
ValidStaticBlockType	Error	Identifies when a static block is using an invalid type.
VariableName	Warning	Identifies variable names that don't adhere to a selected naming convention.

Anchor to JSON file checksJSON file checks

These checks analyze the syntax, content and structure of JSON files.

Check	Severity	Purpose	Auto-correction
JSONMissingBlock	Error	Identifies when a JSON template file is referencing block types that don't exist.
JSONSyntaxError	Error	Identifies invalid JSON files in themes.
MatchingTranslations	Warning	Identifies missing or additional translations in locale files.	Yes
ValidHTMLTranslation	Warning	Identifies invalid HTML inside translations.

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