site_admin_notice()

site_admin_notice(): void|false

function site_admin_notice() {
	global $wp_db_version, $pagenow;

	if ( ! current_user_can( 'upgrade_network' ) ) {
		return false;
	}

	if ( 'upgrade.php' === $pagenow ) {
		return;
	}

	if ( (int) get_site_option( 'wpmu_upgrade_site' ) !== $wp_db_version ) {
		$upgrade_network_message = sprintf(
			/* translators: %s: URL to Upgrade Network screen. */
			__( 'Thank you for Updating! Please visit the <a href="%s">Upgrade Network</a> page to update all your sites.' ),
			esc_url( network_admin_url( 'upgrade.php' ) )
		);

		wp_admin_notice(
			$upgrade_network_message,
			array(
				'type'               => 'warning',
				'additional_classes' => array( 'update-nag', 'inline' ),
				'paragraph_wrap'     => false,
			)
		);
	}
}