Same here after updating to the latest version. Searched in google and a lot of sites using Page-Links-To plugin is throwing that warning. I think it is due to the fact that the author has updated the plugin today.
I usually download plugins to my pc and upload via ftp so I uploaded an older version and it works fine for the time being.
Hi all. I wasn’t able to reproduce this issue, but I threw in some code to hopefully protect against that situation. Please update to 2.7.1 (just released it, so keep hitting Dashboard » Updates until you see it).