I have a Spotify Premium Account. It works fine on my MacBook Pro, and it used to work on my iPhone 4Gs until a few days ago.
When I open the app on the iPhone, I am prompted to login either with Facebook or with Spotify details. When I attempt the Facebook option, the screen goes blue with the Facebook logo for one second and then I am retured to the iPhone folder. When I attempt to login with Spotify details (which I have confirmed are correct), I get the following message: "Login failed. Could not login to Spotify Maybe you've changed or misspelled the password?"
Device’s Operating System
Is your device jailbroken?
My Spotify version
My provider and country