There is a configuration file in your website or a configuration entry in a plugin or theme that uses an absolute path to your website. The file system structure of cPanel is different from Plesk. Your root path in Plesk is /var/www/vhosts/<your subscription domain>/<your document root directory>, for example:
/var/www/vhosts/example.com/httpdocs
First, please check your wp-config.php file, if a path is mentioned in some "DEFINE" statement that does not match the new environment.
Please also check your .htaccess file for such paths.
Then make sure that no third-party plugins are active that have such a configuration.