Attribute 'unitOfMeasure' must appear on element

XML Parsing Error at Line 30, Column 24: cvc-complex-type.4: Attribute 'unitOfMeasure' must appear on element 'WaistSize'

This error might appear when you need to send new products to Amazon. When you set the mapping in the Creation Profile, please make sure to put not only the values to the Size attributes, but also add Units of Measure. Please refer to this article to read more about Creation Profiles.