After i updated the boards SAM version 1.6.8 i get
Arduino: 1.6.9 (Windows 7), Board: "Arduino Due (Programming Port)"
Board arduino_due_x_dbg (platform sam, package arduino) is unknown
Error compiling for board Arduino Due (Programming Port).
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
EDITED
Made a clean installation of IDE 1.6.10 and everything is ok now