This error typically means that one or more of your boxes exceeds the dimensions guidance from UPS, Amazon's only carton contents API partnered carrier.
UPS specifies the following weight and size limits for shipments boxes:
Packages can be up to 150 lbs.
Packages can be up to 165 inches in length and girth combined.
Packages can be up to 108 inches in length.
Packages with a large size-to-weight ratio require special pricing and dimensional weight calculations.