Full Error Message:
Invalid Multi-SKU item id supplied with variations
Please remove the product(s) from eBay and re-list them to resolve this. If you”re seeing this error message, you may have tried to add or remove variation information that is invalid for this listing.
Error: Invalid Multi-SKU item id supplied with variations.
One of the variation SKUs may currently exist on eBay.
Delete and purge the listing in ChannelUnity which will send a delete request to eBay to remove the listing, wait 20 minutes, and then upload the product to create a new listing on eBay (note: the old listing will be deleted from eBay with all it’s history).