As of 2025, Pioneer has officially discontinued support for the AVH-4500NEX. They have removed many legacy firmware files from their main download portals. If the official link is dead:
If your AVH-4500NEX is currently working without issues and you are on firmware 1.05 or higher, you can skip the update. However, if you experience any of the following, the is mandatory: pioneer avh-4500nex firmware update