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function is not described

upgrade_400() WP 4.0.0

Execute changes made in WordPress 4.0.0.

No Hooks.

Return

null. Nothing.

Usage

upgrade_400();

Notes

  • Global. Int. $wp_current_db_version The old (current) database version.

Changelog

Since 4.0.0 Introduced.

Code of upgrade_400() WP 5.8.2

function upgrade_400() {
	global $wp_current_db_version;

	if ( $wp_current_db_version < 29630 ) {
		if ( ! is_multisite() && false === get_option( 'WPLANG' ) ) {
			if ( defined( 'WPLANG' ) && ( '' !== WPLANG ) && in_array( WPLANG, get_available_languages(), true ) ) {
				update_option( 'WPLANG', WPLANG );
			} else {
				update_option( 'WPLANG', '' );
			}
		}
	}
}