- Failure | ErrorCode - 21919303 

ShortMessage - The item specific MPN is missing.

LongMessage - The item specific MPN is missing. Add MPN to this listing, enter a valid value, and then try again.

Explanation and resolution:

eBay would require an MPN identifier for a significant percentage of the main categories and the above error would be triggered and returned, when there wasn't any value in that field in the Item Specifics section and the item was been sent to the channel with this missing requirement and in order to bypass the error, a value needs to be added in that field and then the item can be re-listed and re-submitted to the channel.