This error comes up when the variant setting is disabled in the app. 
- To enable, go to Product Management in Settings.
 - Scroll down to Etsy Variation Management 
 - Toggle it on. 
 
Alternatively, to successfully publish a variant product on Etsy, variation mapping is mandatory. 
If the attributes are not mapped, your product will be listed as a Simple product instead of a Variant product. 
Here's how you can resolve this: 
Steps to Map Variations:
- Go to the Profiling section and select the profile the product is assigned to.
 - Scroll to the "Variation Mapping" option.
 
- Map the variant attributes (such as size, color, etc.) for your product in this section.
 - After mapping the variations, save the profile.
 - Then, go to the "All Products" section in the app and click on publish/update on Etsy.