Twitter Login Stopped Working "sorry, that page doesn't exist"

I'm logging users in with twitter using the PFTwitterUtils loginWithBlock: method. This has always worked fine and the name of my app appears above the username and p/w ready for user input.

However, recently (which may or may not correspond to installing Fabric.io) the modal display that appears, after entering the username and password and pressing authorise app, returns this image:

Has something changed with the sdk lately? Or have i made a silly error while changing something. In short, what is the cause of this error?

It turns out that under settings>twitter log in, my application had been switched off in there and therefore it kept throwing up that message. It really should have the capacity to notify the user when such an instance occurs.