Attempt to create a VPS from WHMCS fails with error: Module command error: Virtual Server not found

Symptoms 

Attempt to create a VPS from WHMCS fails with error:

SVM_ERROR: Module command error: Virtual Server not found

Cause

Not all fields from Custom Field documentation were configured for a product during configuration.

Resolution

Make sure that SolusVM WHMCS billing module documentation was followed thoroughly and all mentioned fields from Custom Filed section are added for each product.