Hi, I have experienced the same problem. In one computer I kept on getting the same message.
However, on the other PC, I was able to save with no errors. It could be cache/Aliexpress new design issue. It is intermittent and hit or miss for some people. I'd suggest to try with different PC or devices and see if you can get it working. Or log out of Aliexpress and clear your cache and see if you can get it working.
You can even try with Internet Explorer or Firefox browser, since saving your data does not require Chrome Extensions.