Invalid numeric value “IPv4 shared; IPv6 none” for the “quota” setting.
If anyone is having issues with this error here's how you fix it:
Go to WHMCS admin area and click on Setup > Products and Services
Find the Product that is giving you the error and then open it / edit it
Go to the Module Settings tab and look at the far right, under where you select the WHM Package, find the link Switch to Advanced Mode
Once Advanced Mode is open, look at Web Space Quota, it may say IPV4 Shared; IPv6 None in the text box
Change this field to a numeric value or leave it blank
BOOM Error gone once you accept the order now.