Friendships/show"Could not determine source user."


My PHP-based web app allows users to follow other Twitter users. Before initiating the API follow action, I first request the user’s current friends with ‘friendships/show’ to ensure they aren’t already following the intended user, however for some (not all) users I’m continually returned this error:

{“errors”:[{“code”:163,“message”:“Could not determine source user.”}]}

(along with a 403 forbidden message)

The code works for my personal Twitter account, but there are several users who generate this error. I also can’t find any info on this via Google. Any ideas?