An error has been discovered when offering free packages for sale using WHMCS where the system looks for the payment gateway "Other" and cannot find it because this payment gateway is never meant to be used by clients, only used in the admin area for accounts which don't use any other gateway. The fix also corrects the issue of free hosting accounts being invoices if the user chooses a domain with a balance to pay. To correct the issue, please download and follow the instructions in the readme of the zip file located here:

https://www.whmcs.com/downloads/freeorderfix.zip
If you experience any other issues, please let me know.