Error: #121984 A package in a Mexico shipment must have a Merchandise Description
The UPS Ship APIs recently were updated for Mexico and while it appears you have a description entered, it isn't passed in older versions of NRGship Pro for UPS because it wasn't necessary. Upgrading to build x331 or above of NRGship Pro for UPS (or NRGship FM for UPS) will resolve this error. Contact NRGship support if you need assistance upgrading.