Quote Originally Posted by RescoCCC View Post
Are you using Numinix Product Fields or the UPC/ISBN mod from software addons? If the latter, that is likely the problem. You need to use the former.
Now I just set it to "false", and google is not giving me errors any more, I also added "MPN" for each product, so don't know which one solved google error issue. But I got another issue "broken images" on merchant center, but when I click through the links, all the images are there on my website! it seems that lately google frequently gave me problems even though I didn't change anything on my website.