In order to fix this you must change the item back to what it was when the listing ended.
Most of the time this will be stock that the customer changed.
For example:
--if the stock now says 25 and you are getting this error, you must change the stock back to 0 and hit UPDATE ITEM.
--At this point you can add back in the 25 and now do a RETRY CHANNEL RELIST
--If you get another error fix as normal and then try another RETRY CHANNEL RELIST and that will list the item as intended.