Plugin need to compatible with PHP version 8.0

This is to let you know that we are usinf EventON in our website https://aroramedicaleducation.co.uk. Recently the PHP version of the Hosting server of the website is upgraded. After that, we notice some warnings in the error log of the website. We are getting such type of warning:

PHP message: PHP Warning: Undefined variable $sess in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 17PHP message: PHP Warning: Trying to access array offset on value of type null in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 17PHP message: PHP Warning: Undefined variable $sess in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 24PHP message: PHP Warning: Trying to access array offset on value of type null in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 24PHP message: PHP Warning: Cannot modify header information – headers already sent by (output started at /www/arora_729/public/wp-content/plugins/eventON/includes/class-frontend.php:181) in /www/arora_729/public/wp-includes/pluggable.php on line 1416PHP message: PHP Warning: Cannot modify header information – headers already sent by (output started at /www/arora_729/public/wp-content/plugins/eventON/includes/class-frontend.php:181) in /www/arora_729/public/wp-includes/pluggable.php on line 1419PHP message: PHP Warning: Undefined variable $sess in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 540PHP message: PHP Warning: Trying to access array offset on value of type null in /www/arora_729/public/wp-content/themes/astra-child/mock-test-result-tamplate.php on line 540″ while reading upstream, client: 52.167.144.30, server: aroramedicaleducation.co.uk, request: “GET /mock-center-result/?exam_id=34042&result_id=11282&free_user_id= HTTP/1.1”, upstream: “fastcgi://unix:/var/run/php8.0-fpm-arora.sock:”, host: “aroramedicaleducation.co.uk:28215”.

Please update the plugin code so that it will be compatible with PHP version 8.0.

Awaiting for your early response.

The page I need help with: [log in to see the link]