I've been having trouble logging in to Spotify since moving to Mint 18.2. The current stable release of spotify-client doesn't seem to successfully work with firefox. I resolved the issue by updating my sources file (/etc/apt/sources.list.d/spotify.list) to
then running apt-get update and apt-get upgrade
Pro: the login dialogue for Facebook works again
Con: it is a testing release. I haven't used it much yet but so far so good.