Error "The billing system is temporarily unavailable‬" in SolusVM 2 Client Area

Symptoms 

Error "The billing system is temporarily unavailable‬" in SolusVM 2 Client Area

WHMCS Pre-paid module was recently configured

Cause

Post-Pay addon is active. The corresponding error reporting is planned to be improved in a scope of SVM2-6342.

Resolution

The Pre-paid module installation comes additionally with SolusVM 2 Post-Paid addon by default, therefore you need to turn it off:
WHMCS UI > Addons > SolusVM 2
 
Set Billing Integration Settings to None in SolusVM 2 UI > Settings > Billing Integration