Undefined constant Error in the Monthly Orders Report
Symptom
After updating to WHMCS 8.6.1, you may experience an Undefined Constant
error when viewing the Monthly Orders report in PHP 8.1 environments:
Error: Undefined constant "tbladdons" in /path/to/whmcs/modules/reports/monthly_orders.php:81
Hotfix
We have created a hotfix for WHMCS 8.6.1 to resolve the error:
Workaround
Upgrade your hosting environment to PHP 7.4.