Please specify a valid return policy. ErrorCode: 21916328

Complete error message: Please specify a valid return policy. ErrorCode: 21916328

This error means that you need to update the return policy you’ve chosen for your listings.

Go to:

> Channels page
> eBay settings
> List to eBay

Please, make sure that the returns policy you picked is updated (you do this step on eBay directly)

postage policy