as Kane mentioned, 9 months is the prime secondary 'fear' stage. It's also a pretty formative stage and mishandling those fears can 'set' them. Do not punish him for acting fearful (this reinforces you or it as something that is, indeed, fearful) and don't force him to interact with whatever is frightening him. Encourage, instead, exploration and investigation of these suddenly fearful objects or events. Reward heavily for any small bravery toward conquering this and ignore the rest.
Pups of this age will often do the "OH MY GOD, IT's A TRASH CAN! (or other random everyday object the have seen 500 times) thing. You don't want to coddle him and thus reward this behavior, but nor do you want to force him if it's pushing him over threshold. Most scary things in my household dispense cheese. The cheese just chills there, the pup can get it if he is brave enough to.
Generally, in a normal pup, the fear stage doesn't last long. If your pup is a fearful pup to begin with it can last longer, and how you handle it can be a turning point that lasts a lifetime