console that has not been connected to Xbox Live in years—or perhaps you are setting up a modded console (RGH/JTAG)—you have likely encountered the keyword. This refers to the Xbox 360 Dashboard System Update 2.0.17559.0 , typically packaged as a USB-installable zip file.
Fixing the "grey avatar" glitch by installing the full official update package which includes avatar and Kinect runtime assets. systemupdate17559usbzip
Now, go forth and update with confidence. console that has not been connected to Xbox