GOOGLE WRITES: We encourage you to tell affected readers (perhaps via a blog post), that if they use a non-Google Account to follow your blog, they need to sign up for a Google Account, and re-follow your blog. With a Google Account, they’ll get blogs added to their Reading List, making it easier for them to see the latest posts and activity of the blogs they follow.
http://buzz.blogger.com/2015/12/an-update-on-google-friend-connect.html