After updating to WHMCS 8.12.0, users of the cPanel Licensing addon module may encounter an Oops! error when accessing the module in the WHMCS Admin Area, and when running the system cron tasks (the cron.php script):

Whoops\Exception\ErrorException: Cannot make static method WHMCS\Module\Addon\Setting::getValue() non static in class WHMCS\Module\Addon\Cpanel\Licensing\Settings\AbstractSetting in unknown:0

We have created a hotfix for WHMCS 8.12.0 to correct the issue. You can download it at:

https://whmcs.community/files/file/205-fatal-error-in-cpanel-licensing-addon-module/ 

Remove the /modules/addons/cpanellicensing/hooks.php file from your WHMCS installation's files.