I have successfully implemented OAuth communication with Yahoo! to retrieve a user's contacts and it has worked fine with the handful of users I have tested; however, one user I attempted to pull contacts from results in a 503 error with a response containing:

....
<error>not available</error>
<errorDetail>new user</errorDetail>
....

The user in question has successfully authenticated with Yahoo! OAuth and has a valid access token; it is only when I make the request to the contacts API that I get the above error. I am currently using the old retrieval implementation rather than a YQL query. If I use the YQL console to access that same user's contacts with 'select * from social.contacts where guid=me' the contacts are returned successfully.

Thanks