I am getting the same error. Is there another thread addressing this? if yes please provide link. If no, someone please help.
Yesterday my import was working fine.
We have about 2,500 variants on our site. We have three options on ALL our variants. Today I started removing the third option as it is not needed. I updated about 70 variants. At that point my co-worker tried to import the csv file while I was working on this change. So in the import file there were three options but on some variants the third option was blank. This is when we received the error. I added the third option back to those products. We exported the inventory file and re-imported it. It worked with no errors.
My theory is the option has to be removed from all products in order for the import to work. I can't have the third option columns with some variants with values and other variants with no value.
Hope this helps get the thread going. Any help will be greatly appreciated. Thanks