The error may simply be a sign-in issue, which sometimes occurs when the Play Store is updated. The first trick is to go into your phone's main Settings menu .
Swipe down from the top of your phone. Top of Android phone with arrow indicating to swipe down. From your notifications, select Account Action Required.
To resolve this error, please log out of your default Google Account then you will be able to use the Add-on with the account you installed it on.
I had the same problem. My solution was to uninstall and reinstall Google+ and everything worked fine after that.
