ctions() ) );
	}

	/**
	 * Default upgrade message (to Pro version).
	 *
	 * @since 1.9
	 *
	 * @return string
	 */
	protected function default_upgrade_message() {
		return sprintf(
			'%s <a href="%s">%s</a>',
			__( 'To enable this feature, you need Polylang Pro.', 'polylang' ),
			'https://polylang.pro',
			__( 'Upgrade now.', 'polylang' )
		);
	}

	/**
	 * Allows child classes to display an upgrade message.
	 *
	 * @since 1.9
	 *
	 * @return string
	 */
	public function get_upgrade_message() {
		return 'preview' === $this->active_option ? $this->default_upgrade_message() : '';
	}

	/**
	 * Get the buttons.
	 *
	 * @since 1.9
	 *
	 * @return string[] An array of html fragment for the buttons.
	 */
	public function get_buttons() {
		return $this->buttons;
	}
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class &quot;PLL_Settings_Module&quot; not found in /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/modules/sync/settings-sync.php:11
Stack trace:
#0 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/composer/ClassLoader.php(576): include()
#1 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/composer/ClassLoader.php(427): Composer\Autoload\{closure}('/home/sanattv/p...')
#2 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Business/Sync.php(46): Composer\Autoload\ClassLoader-&gt;loadClass('PLL_Settings_Sy...')
#3 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Abstract_Option.php(63): WP_Syntex\Polylang\Options\Business\Sync-&gt;get_data_structure()
#4 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Options.php(116): WP_Syntex\Polylang\Options\Abstract_Option-&gt;__construct(Array)
#5 [internal function]: WP_Syntex\Polylang\Options\Options-&gt;register('WP_Syntex\\Polyl...')
#6 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Registry.php(51): array_map(Array, Array)
#7 /home/sanattv/public_html/staging.sanat.international/wp-includes/class-wp-hook.php(343): WP_Syntex\Polylang\Options\Registry::register(Object(WP_Syntex\Polylang\Options\Options))
#8 /home/sanattv/public_html/staging.sanat.international/wp-includes/class-wp-hook.php(365): WP_Hook-&gt;apply_filters('', Array)
#9 /home/sanattv/public_html/staging.sanat.international/wp-includes/plugin.php(522): WP_Hook-&gt;do_action(Array)
#10 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Options.php(567): do_action('pll_init_option...', Object(WP_Syntex\Polylang\Options\Options), 1)
#11 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/Options/Options.php(81): WP_Syntex\Polylang\Options\Options-&gt;init_options_for_current_blog()
#12 /home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/include/class-polylang.php(174): WP_Syntex\Polylang\Options\Options-&gt;__construct()
#13 /home/sanattv/public_html/staging.sanat.international/wp-includes/class-wp-hook.php(341): Polylang-&gt;init('')
#14 /home/sanattv/public_html/staging.sanat.international/wp-includes/class-wp-hook.php(365): WP_Hook-&gt;apply_filters(NULL, Array)
#15 /home/sanattv/public_html/staging.sanat.international/wp-includes/plugin.php(522): WP_Hook-&gt;do_action(Array)
#16 /home/sanattv/public_html/staging.sanat.international/wp-settings.php(593): do_action('plugins_loaded')
#17 /home/sanattv/public_html/staging.sanat.international/wp-config.php(102): require_once('/home/sanattv/p...')
#18 /home/sanattv/public_html/staging.sanat.international/wp-load.php(50): require_once('/home/sanattv/p...')
#19 /home/sanattv/public_html/staging.sanat.international/wp-blog-header.php(13): require_once('/home/sanattv/p...')
#20 /home/sanattv/public_html/staging.sanat.international/index.php(17): require('/home/sanattv/p...')
#21 {main}
  thrown in <b>/home/sanattv/public_html/staging.sanat.international/wp-content/plugins/polylang-pro/vendor/wpsyntex/polylang/modules/sync/settings-sync.php</b> on line <b>11</b><br />