Relist Items: Success

ebayid:82 Failure | ErrorCode:21916635 

ShortMessage:Invalid Multi-SKU item id. 

LongMessage:Invalid Multi-SKU item id supplied with variations.

Problem: You are getting this error because the original item was not a Multi-SKU item and you are trying to relist it as a Multi-SKU item. 

If the original item was not listed as a Multi-SKU item, you cannot change it to be a Multi-SKU item during relist (or revise). You will need to create a new listing as a Multi-SKU item.

Solution:  You have to export and relist the whole variation