When the item number appears with various references or the article is provided with non-valid versions:
This is due to a product which was posted online in an eBay category that does not support multi-version mode ==> Various products in the database.
At present, the solution is to delete these products from the database, using the table: __DB_PREFIX__.’ebay_product’ before repeating the synchronization. To do this, go into your phpmyadmin, click on the table named ebay_product and then empty it. Navigate back to your back-office and synchronize.
See Multi-Version Listings for more information.