[After creating a banner I'm getting error 500 instead of redirecting to destination]

Running AdServer 5.3.0. Nginx.

After installing, I started working on AdServer by configuring AdsSense and all worked perfectly. However, yesterday I created a custom banner pointing to a specific client page. 

The image is properly displayed but when i click the link which points to my ads server instance, I'm getting 500 error. Additionally, nginx error log is displayed.

2021/12/17 17:16:50 [error] 245686#245686: *1687747 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function Symfony\Polyfill\Intl\Idn\mb_chr() in /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php:290
Stack trace:
#0 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php(335): Symfony\Polyfill\Intl\Idn\Idn::mapCodePoints()
#1 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php(163): Symfony\Polyfill\Intl\Idn\Idn::process()
#2 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/bootstrap.php(140): Symfony\Polyfill\Intl\Idn\Idn::idn_to_ascii()
#3 /var/www/ads/www/delivery/cl.php(2739): idn_to_ascii()
#4 /var/www/ads/www/delivery/cl.php(3421): MAX_redirect()
#5 {main}
  thrown in /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php on line 290" while reading response header from upstream, client: 95.60.38.52, server: ads.server.es, request: "GET /www/delivery/cl.php?bannerid=13&zoneid=16&sig=cd1b3450c9b5d171408c1684cfac68223d7d4ef329c30e458952cc968dbc1b41&dest=https%3A%2F%2Flabombadenavidad.es%2Fbuscar-loteria HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php-fpm.sock:", host: "ads.server.es"
2021/12/17 17:17:35 [error] 245686#245686: *1687747 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function Symfony\Polyfill\Intl\Idn\mb_chr() in /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php:290
Stack trace:
#0 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php(335): Symfony\Polyfill\Intl\Idn\Idn::mapCodePoints()
#1 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php(163): Symfony\Polyfill\Intl\Idn\Idn::process()
#2 /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/bootstrap.php(140): Symfony\Polyfill\Intl\Idn\Idn::idn_to_ascii()
#3 /var/www/ads/www/delivery/cl.php(2739): idn_to_ascii()
#4 /var/www/ads/www/delivery/cl.php(3421): MAX_redirect()
#5 {main}
  thrown in /var/www/ads/lib/vendor/symfony/polyfill-intl-idn/Idn.php on line 290" while reading response header from upstream, client: 95.60.38.52, server: ads.server.es, request: "GET /www/delivery/cl.php?bannerid=13&zoneid=16&sig=cd1b3450c9b5d171408c1684cfac68223d7d4ef329c30e458952cc968dbc1b41&dest=https%3A%2F%2Flabombadenavidad.es%2Fbuscar-loteria HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php-fpm.sock:", host: "ads.server.es"

Can you please support me on this issue?

Thanks!