No matter what age, Han Solo has always had issues with authority, so joining the Empire probably wasn’t his best decision.
Needless to say this did not go over well with his superior officers, and despite Han trying to explain his actions, he’s chewed out for disobeying a direct order with his “maverick heroics” and is demoted to infantryman.
Han was successful, but his maneuver led to him crashing back into a Star Destroyer docking bay.
Unfortunately for Han, this means that his flying career in the Empire is pretty much kaput.