It appears that Facebook is refusing to authorize user requests to find their friends on Twitter’s new Vine social video service. Twitter user @MartinesJeff noticed the error, which reads, "Vine is not authorized to make this Facebook request."
The specificity of the error message is intriguing; it almost looks as though the Vine app was already set up to explain a situation like this. Facebook and Twitter have long been battling each other over access to user data; this past July, Twitter similarly blocked Instagram from using its own friend-finding API, then did the same thing to Tumblr a couple of months later in August. This most recent move from Facebook appears to be the real deal. We've confirmed it on a number of different devices, and while Twitter's only comment has been to refer us back to that notification message, we've reached out to Facebook for comment, and will let you know what we hear.