You can view your eBay product sync errors using the instructions here: Using the eBay Dashboard. Here are some explanations for common errors you may encounter.
Error 107 – The category is not valid, select another category.
This error indicates that the eBay category selected for this item isn’t valid. Please note, the eBay category is different from your store category. Please see the following article for help with eBay categories: eBay Categories
Error 21916608 – Variation cannot be deleted during restricted revise.
This appears to happen after one or more sales happen on a variation listing and a new variation child is being added to the listing. The eBay system has flagged that transactions have happened on the listing and is incorrectly restricting the options that can be revised. To resolve this error, you’ll want to manually end the listing (click Other Item Actions->End Listing) and create a new listing (Map & Post Single Item) in the eBay Dashboard.
Error 10007 – Internal error to the application.
This indicates an error on the eBay server side and not an error in FarApp. This error resolves itself once eBay corrects their issue.
Error 21917098 – The shipping rate table is not applicable for this site.
eBay can on occasion erroneously report this error if you’re attempting to relist an item and your shipping options have changed. Posting the item as a new listing instead of relisting it will usually work and will resolve the error. If you want to list your item as a new listing, please follow the instructions in the “Post an item as a new listing (avoid relisting)” section here:
Using the eBay Dashboard