Some errors.

Hello, Not sure what is the issue. I have PHP version 7.2.31-1+ubuntu18.04.1+deb.sury.org+1

Error Details
=============
An error of type E_ERROR was caused in line 114 of the file /var/www//wp-content/plugins/smart-countdown-fx/includes/helper.php. Error message: Uncaught Error: Call to undefined function simplexml_load_string() in /var/www//wp-content/plugins/smart-countdown-fx/includes/helper.php:114
Stack trace:
#0 /var/www//wp-content/plugins/smart-countdown-fx/smartcountdownfx.php(106): SmartCountdown_Helper::getCounterConfig(Array)
#1 /var/www//wp-content/plugins/smart-countdown-fx/smartcountdownfx.php(975): SmartCountdown_Widget->widget(Array, Array)
#2 /var/www//wp-includes/shortcodes.php(343): SmartCountdown_Widget::short_code(Array, ”, ‘smartcountdown’)
#3 [internal function]: do_shortcode_tag(Array)
#4 /var/www//wp-includes/shortcodes.php(218): preg_replace_callback(‘/\\[(\\[?)(smartc…’, ‘do_shortcode_ta…’, ‘[et_pb_secti…’)
#5 /var/www//wp-includes/class-wp-hook.php(287): do_shortcode(‘[et_pb_secti…’)

Thank you.