When processing UPS orders, you might come across the "Hard 120603 - Invalid Package Reference Value" error.
This error happens when the Customer Order # exceeds the length of 35 characters when using UPS Mail Innovations.
To solve this, you can either:
a) Use shorter Customer Order numbers
b) If that's not possible, remove or replace the reference as this article indicates: https://support.techdinamics.com/solution/articles/227983-adding-reference-numbers-on-labels-step-by-step-guide-