Troubleshooting a ClientRequired: Forbidden Error when deleting quote items
After applying the 8.0.0 update, an Oops fatal PHP error can occur when deleting a line item from a quote:
WHMCS\Exception\Authentication\ClientRequired: Forbidden in /path/to/whmcs/includes/clientfunctions.php:0
Please apply the 8.0.1 Maintenance Release via the Utilities > Update WHMCS page.
A hotfix has been created for 8.0.0 only to resolve this error: