try to make sure that the Game Object ( “first_person_controller” ) are active when the game trying to execute that code. this is because GameObject.Find function only returns active Game Objects.
First make sure first_person_controller name is same as seen in hierarchy.And then check in an if statement whether the specified component is attached to it.
You Cant Just Use “Find”. The Best Way Would Be To Use set a tag on the Object you want to find and use “FindWithTag” instead of “Find”. Works Every time.
In one of the screenshots you posted, I see there’s an arrow pointing down on the “first_person_controller” object, indicating it has children.
Make sure the MouseLook script is attached to the object first_person_controller and NOT its children, or else you will get a null with you current code.