Hello fellow developer,
I just found a somewhat critical bug/issue in DW that i think you should know about before you upgrade to 8.4.1.0.
If you site uses ProductCategoriesField and has multiple languages you need to read this!
Prior to 8.4.1.0 ProductCategoriesFields weren't part of Fields and therefore values were not save to other languagevariants when saved.
But in 8.4.1.x it's now possible to have fieldvalues shared between languages on ProductCategoriFields aswell, the problem is that it's turned on by default when updating and this means that after updating, every update your client does on their products, could override fields on the other languages.
Workaround - Make sure you check off all ProductCategoryFields in 'Management center -> Ecommerce -> Advanced configuration -> Fields' after you update.
I couldn't find this under 'breaking changes'/'important notes', but i think it should be in there, because it could cause big problems down the road if clients edit products, and you did nothing.
BR
Martin Nielsen
Co3