In January 2024, Theme Check 2.x was integrated into the [admin code editor](/docs/storefronts/themes/tools/online-editor), the [VS Code extension](/docs/storefronts/themes/tools/cli/language-server), and [Shopify CLI](/docs/storefronts/themes/tools/cli/cli-2/commands).

On this page, you can learn about the differences between Theme Check 1.x and 2.x, and how to update your theme development environment accordingly.

## CLI changes

The support for check categories has been removed in the new version. As a result, the `--category` and `--exclude-category` flags are no longer available.

The decision to remove these options was made to simplify the API and reduce the noise on the CLI's `--help`. While this might require some users to create a subset of the config for performance-related checks, the new framework's ability to extend multiple configurations makes this a more efficient approach. For more details about flags, please refer to the [commands reference](/docs/storefronts/themes/tools/theme-check/commands).

## Configuration changes

In Theme Check 2.x, the `extends` option has been updated. It now supports values such as `theme-check:all`, `theme-check:recommended`, and `theme-check:theme-app-extension`, but also supports a list of configuration files and third-party modules. For more details, please refer to the [configuration file reference](/docs/storefronts/themes/tools/theme-check/configuration).

The `require` option no longer supports custom Ruby checks. If you need to create your own custom checks or use a third-party set of checks with Theme Check 2.x, refer to the [Creating your own checks](https://github.com/Shopify/theme-tools/blob/main/docs/theme-check-common/writing-your-own-check) guide.

## Check compatibility table

Theme Check 2.x introduces changes to the collection of checks, including removals, renames, optimizations, and regrouping. The table below compares Theme Check 1.x and 2.x, outlining these changes.

| **Theme Check 1.x** | **Theme Check 2.x** |
| :---- | :---- |
| AppBlockValidTags | AppBlockValidTags |
| AssetPreload | AssetPreload |
| AssetSizeAppBlockCSS | AssetSizeAppBlockCSS |
| AssetSizeAppBlockJavaScript | AssetSizeAppBlockJavaScript |
| AssetSizeCSS | AssetSizeCSS |
| AssetSizeCSSStylesheetTag | AssetSizeCSS |
| AssetSizeJavaScript | AssetSizeJavaScript |
| - | BlockIdUsage |
| AssetUrlFilters | RemoteAsset |
| CdnPreconnect | CdnPreconnect |
| ContentForHeaderModification | ContentForHeaderModification |
| ConvertIncludeToRender | DeprecatedTag |
| DefaultLocale | - |
| DeprecateBgsizes | DeprecateBgsizes |
| DeprecatedFilter | DeprecatedFilter |
| DeprecatedGlobalAppBlockType | - |
| DeprecatedTags | DeprecatedTag |
| DeprecateLazysizes | DeprecateLazysizes |
| - | DuplicateRenderSnippetArguments |
| - | EmptyBlockContent |
| HtmlParsingError | LiquidHTMLSyntaxError |
| ImgLazyLoading | - |
| ImgWidthAndHeight | ImgWidthAndHeight |
| - | JSONMissingBlock |
| - | LiquidFreeSettings |
| LiquidTag | - |
| MatchingSchemaTranslations | MatchingTranslations |
| MatchingTranslations | MatchingTranslations |
| MissingAsset | MissingAsset |
| MissingEnableComment | - |
| - | MissingRenderSnippetArguments |
| MissingRequiredTemplateFiles | - |
| MissingTemplate | MissingTemplate |
| NestedSnippet | - |
| PaginationSize | PaginationSize |
| ParserBlockingJavaScript | ParserBlockingScript |
| ParserBlockingScriptTag | ParserBlockingScript |
| RemoteAsset | RemoteAsset |
| RequiredDirectories | - |
| RequiredLayoutThemeObject | RequiredLayoutThemeObject |
| SchemaJsonFormat | - |
| - | SchemaPresetsBlockOrder |
| - | SchemaPresetsStaticBlocks |
| SpaceInsideBraces | - |
| SyntaxError | LiquidHTMLSyntaxError |
| TemplateLength | - |
| TranslationKeyExists | TranslationKeyExists |
| - | UnclosedHTMLElement |
| UndefinedObject | UndefinedObject |
| UnknownFilter | UnknownFilter |
| - | UniqueDocParamNames |
| - | UniqueStaticBlockId |
| - | UnrecognizedRenderSnippetArguments |
| - | UnsupportedDocTag |
| UnusedAssign | UnusedAssign |
| - | UnusedDocParam |
| UnusedSnippet | - |
| ValidHTMLTranslation | ValidHTMLTranslation |
| ValidJson | JSONSyntaxError |
| ValidSchema | ValidSchema |
| - | ValidBlockTarget |
| - | ValidContentForArguments |
| - | ValidDocParamNames |
| - | ValidDocParamTypes |
| - | ValidLocalBlocks |
| - | ValidRenderSnippetArgumentTypes |
| - | ValidSchemaName |
| - | ValidSettingsKey |
| - | ValidStaticBlockType |