Troubleshooting an InvalidArgumentException: Data missing in Carbon.php:425 Error
After upgrading your server environment to PHP 7.4 and navigating to the Help > System Health Status page, the following error is displayed:
InvalidArgumentException: Data missing in /path/to/whmcs/cs/vendor/nesbot/carbon/src/Carbon/Carbon.php:425
The version of PHP being used is not compatible with your current WHMCS release.
PHP compatibility is itemised at https://docs.whmcs.com/System_Environment_Guide#Version_Compatibility_2
Downgrade to an appropriate version of PHP for use with your current WHMCS release.
Example: For WHMCS v7.10 use PHP v7.3.
Please contact your server admin/hosting provider for assistance changing the PHP version.