Source: wp-includes/update.php

Filters

core_version_check_locale

Filters the locale requested for WordPress core translations.

apply_filters( 'core_version_check_locale', string $locale )

Parameters:

• $locale (string) – Current locale from get_locale()

Returns: string – Locale code to use for update check

Since: 2.8.0

Example:

// Force English locale for update checks
add_filter( 'core_version_check_locale', function( $locale ) {
    return 'en_US';
});

core_version_check_query_args

Filters the query arguments sent to WordPress.org core version check.

apply_filters( 'core_version_check_query_args', array $query )

Parameters:

• $query (array):
  • version – WordPress version
  • php – PHP version
  • locale – Locale code
  • mysql – MySQL version
  • local_package – Value of $wp_local_package global
  • blogs – Number of sites
  • users – Number of users
  • multisite_enabled – 1 or 0
  • initial_db_version – DB version at installation
  • myisam_tables – List of MyISAM tables (since 6.1.0)
  • extensions – PHP extensions and versions (since 6.1.0)
  • platform_flags – OS and bit info (since 6.1.0)
  • image_support – GD/Imagick format support (since 6.1.0)

Returns: array

Since: 4.9.0

Warning: Modifying this data may prevent security updates. Use with extreme caution.

plugins_update_check_locales

Filters the locales requested for plugin translations.

apply_filters( 'plugins_update_check_locales', string[] $locales )

Parameters:

• $locales (string[]) – Available locales from get_available_languages()

Returns: string[] – Array of locale codes

Since: 3.7.0 (4.5.0 changed default to all locales)

themes_update_check_locales

Filters the locales requested for theme translations.

apply_filters( 'themes_update_check_locales', string[] $locales )

Parameters:

• $locales (string[]) – Available locales from get_available_languages()

Returns: string[] – Array of locale codes

Since: 3.7.0 (4.5.0 changed default to all locales)

update_plugins_{$hostname}

Filters update response for plugins using custom Update URI header.

apply_filters( "update_plugins_{$hostname}", array|false $update, array $plugin_data, string $plugin_file, string[] $locales )

Dynamic portion: $hostname is the hostname from the plugin’s Update URI header.

Parameters:

• $update (array|false) – Update data or false for no update:
  • id – Plugin URI identifier
  • slug – Plugin slug
  • version – Available version
  • url – Plugin details URL
  • package – Update ZIP URL (optional)
  • tested – WordPress version tested against (optional)
  • requires_php – Minimum PHP version (optional)
  • autoupdate – Auto-update flag (optional)
  • icons – Plugin icons (optional)
  • banners – Plugin banners (optional)
  • banners_rtl – RTL banners (optional)
  • translations – Translation updates (optional)
• $plugin_data (array) – Plugin header data
• $plugin_file (string) – Plugin basename
• $locales (string[]) – Installed locales

Returns: array|false

Since: 5.8.0

Example:

// Handle updates for plugins hosted at updates.example.com
add_filter( 'update_plugins_updates.example.com', function( $update, $plugin_data, $plugin_file, $locales ) {
    // Query your update server
    $response = wp_remote_get( "https://updates.example.com/api/plugin/{$plugin_data['slug']}" );
    
    if ( is_wp_error( $response ) ) {
        return false;
    }
    
    return json_decode( wp_remote_retrieve_body( $response ), true );
}, 10, 4 );

update_themes_{$hostname}

Filters update response for themes using custom Update URI header.

apply_filters( "update_themes_{$hostname}", array|false $update, array $theme_data, string $theme_stylesheet, string[] $locales )

Dynamic portion: $hostname is the hostname from the theme’s Update URI header.

Parameters:

• $update (array|false) – Update data or false:
  • id – Theme URI identifier
  • theme – Theme directory name
  • version – Available version
  • url – Theme details URL
  • package – Update ZIP URL (optional)
  • tested – WordPress version tested against (optional)
  • requires_php – Minimum PHP version (optional)
  • autoupdate – Auto-update flag (optional)
  • translations – Translation updates (optional)
• $theme_data (array) – Theme header data
• $theme_stylesheet (string) – Theme stylesheet/slug
• $locales (string[]) – Installed locales

Returns: array|false

Since: 6.1.0

wp_get_update_data

Filters the update data returned for admin UI display.

apply_filters( 'wp_get_update_data', array $update_data, array $titles )

Parameters:

• $update_data (array):
  • counts – Array of update counts (plugins, themes, wordpress, translations, total)
  • title – Combined title string
• $titles (array) – Individual title strings

Returns: array

Since: 3.5.0

Example:

// Add custom update count
add_filter( 'wp_get_update_data', function( $data, $titles ) {
    $data['counts']['custom'] = 3;
    $data['counts']['total'] += 3;
    return $data;
}, 10, 2 );

Actions

wp_maybe_auto_update

Fires during cron to start the auto-update process.

do_action( 'wp_maybe_auto_update' )

Since: 3.9.0

Behavior: Triggered by wp_version_check() when running via cron and not already in update handler.

Default callback: wp_maybe_auto_update() (priority 10)

Registered Action Hooks

The following hooks are registered at the bottom of update.php:

Admin Init Hooks

add_action( 'admin_init', '_maybe_update_core' );
add_action( 'admin_init', '_maybe_update_plugins' );
add_action( 'admin_init', '_maybe_update_themes' );

Cron Event Hooks

add_action( 'wp_version_check', 'wp_version_check' );
add_action( 'wp_update_plugins', 'wp_update_plugins' );
add_action( 'wp_update_themes', 'wp_update_themes' );
add_action( 'wp_maybe_auto_update', 'wp_maybe_auto_update' );
add_action( 'wp_delete_temp_updater_backups', 'wp_delete_all_temp_backups' );

Page Load Hooks

// Plugin checks on relevant admin pages
add_action( 'load-plugins.php', 'wp_update_plugins' );
add_action( 'load-update.php', 'wp_update_plugins' );
add_action( 'load-update-core.php', 'wp_update_plugins' );

// Theme checks on relevant admin pages
add_action( 'load-themes.php', 'wp_update_themes' );
add_action( 'load-update.php', 'wp_update_themes' );
add_action( 'load-update-core.php', 'wp_update_themes' );

Other Hooks

add_action( 'update_option_WPLANG', 'wp_clean_update_cache', 10, 0 );
add_action( 'init', 'wp_schedule_update_checks' );

Conditional Loading

Update hooks only register on main site or network admin, excluding Ajax:

if ( ( ! is_main_site() && ! is_network_admin() ) || wp_doing_ajax() ) {
    return;
}

This prevents update checks from running on subsites in multisite installations.

Related Hooks (External)

These hooks are used by the update system but defined elsewhere:

• upgrader_process_complete – Fires after updates complete (class-wp-upgrader.php)
• auto_update_{$type} – Filter auto-update decision per item type
• auto_update_plugin – Filter individual plugin auto-update
• auto_update_theme – Filter individual theme auto-update
• auto_update_core – Filter core auto-update
• automatic_updater_disabled – Disable all auto-updates