Troubleshooting an InvalidArgumentException: Data missing in Carbon.php:425 Error
After upgrading your server environment to PHP 7.4, you see the following error at Help > System Health Status:
InvalidArgumentException: Data missing in /path/to/whmcs/cs/vendor/nesbot/carbon/src/Carbon/Carbon.php:425
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Your system's PHP version is not compatible with your current WHMCS version.
For more information on WHMCS's PHP version requirements, see System Environment Guide.
Move to a compatible PHP version for your current WHMCS release. For example, for WHMCS 7.10 you could use PHP 7.3.
For help with this process, contact your hosting provider or system administrator.