#include <Serial.h> gives the error. I can not find this file. I tried to delete Serial.h, giving other errors.
ArtNetLED: 176: error: variable 'ipPage' must be const in order to be put into read-only section by '__attribute __ ((progmem))'
char ipPage [] PROGMEM =
^
ArtNetLED: 201: error: variable 'artnetPage' must be const in order to be put into read-only section by '__attribute __ ((progmem))'
char artnetPage [] PROGMEM =
^
ArtNetLED: 223: error: variable 'ledPage' must be const in order to be put into read-only section by '__attribute __ ((progmem))'
char ledPage [] PROGMEM =