Title: Theme_Upgrader::check_package Published: April 25, 2014 Last modified: February 24, 2026 --- # Theme_Upgrader::check_package( string $source ): string|󠀁[WP_Error](https://developer.wordpress.org/reference/classes/wp_error/)󠁿 ## In this article * [Description](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#description) * [Parameters](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#parameters) * [Return](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#return) * [Source](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#source) * [Related](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#related) * [Changelog](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#changelog) [ Back to top](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#wp--skip-link--target) Checks that the package source contains a valid theme. ## 󠀁[Description](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#description)󠁿 Hooked to the [‘upgrader_source_selection’](https://developer.wordpress.org/reference/hooks/upgrader_source_selection/) filter by [Theme_Upgrader::install()](https://developer.wordpress.org/reference/classes/theme_upgrader/install/). ## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#parameters)󠁿 `$source`stringrequired The path to the downloaded package source. ## 󠀁[Return](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#return)󠁿 string|[WP_Error](https://developer.wordpress.org/reference/classes/wp_error/) The source as passed, or a [WP_Error](https://developer.wordpress.org/reference/classes/wp_error/) object on failure. ## 󠀁[Source](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#source)󠁿 ```php public function check_package( $source ) { global $wp_filesystem; $wp_version = wp_get_wp_version(); $this->new_theme_data = array(); if ( is_wp_error( $source ) ) { return $source; } // Check that the folder contains a valid theme. $working_directory = str_replace( $wp_filesystem->wp_content_dir(), trailingslashit( WP_CONTENT_DIR ), $source ); if ( ! is_dir( $working_directory ) ) { // Confidence check, if the above fails, let's not prevent installation. return $source; } // A proper archive should have a style.css file in the single subdirectory. if ( ! file_exists( $working_directory . 'style.css' ) ) { return new WP_Error( 'incompatible_archive_theme_no_style', $this->strings['incompatible_archive'], sprintf( /* translators: %s: style.css */ __( 'The theme is missing the %s stylesheet.' ), 'style.css' ) ); } // All these headers are needed on Theme_Installer_Skin::do_overwrite(). $new_theme_data = get_file_data( $working_directory . 'style.css', array( 'Name' => 'Theme Name', 'Version' => 'Version', 'Author' => 'Author', 'Template' => 'Template', 'RequiresWP' => 'Requires at least', 'RequiresPHP' => 'Requires PHP', ) ); if ( empty( $new_theme_data['Name'] ) ) { return new WP_Error( 'incompatible_archive_theme_no_name', $this->strings['incompatible_archive'], sprintf( /* translators: %s: style.css */ __( 'The %s stylesheet does not contain a valid theme header.' ), 'style.css' ) ); } /* * Parent themes must contain an index file: * - classic themes require /index.php * - block themes require /templates/index.html or block-templates/index.html (deprecated 5.9.0). */ if ( empty( $new_theme_data['Template'] ) && ! file_exists( $working_directory . 'index.php' ) && ! file_exists( $working_directory . 'templates/index.html' ) && ! file_exists( $working_directory . 'block-templates/index.html' ) ) { return new WP_Error( 'incompatible_archive_theme_no_index', $this->strings['incompatible_archive'], sprintf( /* translators: 1: templates/index.html, 2: index.php, 3: Documentation URL, 4: Template, 5: style.css */ __( 'Template is missing. Standalone themes need to have a %1$s or %2$s template file. Child themes need to have a %4$s header in the %5$s stylesheet.' ), 'templates/index.html', 'index.php', __( 'https://developer.wordpress.org/themes/advanced-topics/child-themes/' ), 'Template', 'style.css' ) ); } $requires_php = isset( $new_theme_data['RequiresPHP'] ) ? $new_theme_data['RequiresPHP'] : null; $requires_wp = isset( $new_theme_data['RequiresWP'] ) ? $new_theme_data['RequiresWP'] : null; if ( ! is_php_version_compatible( $requires_php ) ) { $error = sprintf( /* translators: 1: Current PHP version, 2: Version required by the uploaded theme. */ __( 'The PHP version on your server is %1$s, however the uploaded theme requires %2$s.' ), PHP_VERSION, $requires_php ); return new WP_Error( 'incompatible_php_required_version', $this->strings['incompatible_archive'], $error ); } if ( ! is_wp_version_compatible( $requires_wp ) ) { $error = sprintf( /* translators: 1: Current WordPress version, 2: Version required by the uploaded theme. */ __( 'Your WordPress version is %1$s, however the uploaded theme requires %2$s.' ), $wp_version, $requires_wp ); return new WP_Error( 'incompatible_wp_required_version', $this->strings['incompatible_archive'], $error ); } $this->new_theme_data = $new_theme_data; return $source; } ``` [View all references](https://developer.wordpress.org/reference/files/wp-admin/includes/class-theme-upgrader.php/) [View on Trac](https://core.trac.wordpress.org/browser/tags/6.9.4/src/wp-admin/includes/class-theme-upgrader.php#L562) [View on GitHub](https://github.com/WordPress/wordpress-develop/blob/6.9.4/src/wp-admin/includes/class-theme-upgrader.php#L562-L669) ## 󠀁[Related](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#related)󠁿 | Uses | Description | | [wp_get_wp_version()](https://developer.wordpress.org/reference/functions/wp_get_wp_version/)`wp-includes/functions.php` | Returns the current WordPress version. | | [is_php_version_compatible()](https://developer.wordpress.org/reference/functions/is_php_version_compatible/)`wp-includes/functions.php` | Checks compatibility with the current PHP version. | | [is_wp_version_compatible()](https://developer.wordpress.org/reference/functions/is_wp_version_compatible/)`wp-includes/functions.php` | Checks compatibility with the current WordPress version. | | [get_file_data()](https://developer.wordpress.org/reference/functions/get_file_data/)`wp-includes/functions.php` | Retrieves metadata from a file. | | [__()](https://developer.wordpress.org/reference/functions/__/)`wp-includes/l10n.php` | Retrieves the translation of $text. | | [trailingslashit()](https://developer.wordpress.org/reference/functions/trailingslashit/)`wp-includes/formatting.php` | Appends a trailing slash. | | [is_wp_error()](https://developer.wordpress.org/reference/functions/is_wp_error/)`wp-includes/load.php` | Checks whether the given variable is a WordPress Error. | | [WP_Error::__construct()](https://developer.wordpress.org/reference/classes/wp_error/__construct/)`wp-includes/class-wp-error.php` | Initializes the error. | [Show 4 more](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#) [Show less](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#) ## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/theme_upgrader/check_package/?output_format=md#changelog)󠁿 | Version | Description | | [3.3.0](https://developer.wordpress.org/reference/since/3.3.0/) | Introduced. | ## User Contributed Notes You must [log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fdeveloper.wordpress.org%2Freference%2Fclasses%2Ftheme_upgrader%2Fcheck_package%2F) before being able to contribute a note or feedback.