Amazon Error 8016: The product data provided was insufficient...

Error 8016: The product data provided was insufficient for creating a variation (parent/child) relationship for SKU [...]. For more information, see http://sellercentral.amazon.co.uk/gp/errorcode/8016.

This error is returned when a variation_theme such as "ColorSize" is used but color_name and/or size_name are not populated.

This is likely to happen when an attribute is slightly different from Amazon's requirements. Such as attributes like "Colour" (not "Color") and "Flavour" (not "Flavor") for example. If "Size" and/or "Color" are empty in the profile, WP-Lister will automatically pull the values from an attribute with the  same name. But if your attribute in Woocommerce is "Colour" not "Color", you'll have to help WP-Lister by telling it to pull the value for "Color" from the attribute "Colour". There are two ways to do this:

• you can use the listing profile where you'd search for "color_name", click the magnifier icon and select the product attribute "Colour", or
• you could tell WP-Lister once and for all that your "Colour" equals Amazon's "Color" attribute by selecting them in the "Map Variation Attributes" box on the advanced settings page.

Amazon Seller Central states the following in regards to this error:

This error occurs when you do not provide enough product data to properly create a variation (parent/child) relationship between products. To create a variation relationship, you must provide a VariationTheme value for both the parent product and the child product. For each child product, you must also provide the variation data that corresponds to the VariationTheme you indicated.

For example, if you designate a VariationTheme value of "SizeColor" for your parent product and child products, you must also provide a specific size and colour for each child product. Or, if you designate a VariationTheme of "Flavor" for your parent product and child products, you must also provide a specific flavour for each child product.