: Note down your speaker and input settings, as a firmware update may initialize/reset some menu items. Step-by-Step Firmware Update Instructions AVR-X520BT
If you'd like to check for a specific update for your region: denon avrx520bt firmware update top
Eliminates random system freezes, unintended shutdowns, or input-switching lag. Prerequisites: What You Need Before Updating : Note down your speaker and input settings,