I had same problem and I think I have solved it. In boards.txt file, I had: ############################################################## diecimila.name=Arduino Duemilanove or Diecimila diecimila.upload.tool=avrdude diecimila.upload.protocol=arduino diecimila.bootloader.tool=avrdude diecimila.bootloader.low_fuses=0xFF diecimila.bootloader.unlock_bits=0x3F diecimila.bootloader.lock_bits=0x0F diecimila.build.f_cpu=16000000L diecimila.build.board=AVR_DUEMILANOVE diecimila.build.core=arduino diecimila.build.variant=standard ## Arduino Duemilanove or Diecimila w/ ATmega328 ## --------------------------------------------- diecimila.menu.cpu.atmega328=ATmega328 diecimila.menu.cpu.atmega328.upload.maximum_size=30720 diecimila.menu.cpu.atmega328.upload.maximum_data_size=2048 diecimila.menu.cpu.atmega328.upload.speed=57600 diecimila.menu.cpu.atmega328.bootloader.high_fuses=0xDA diecimila.menu.cpu.atmega328.bootloader.extended_fuses=0x05 diecimila.menu.cpu.atmega328.bootloader.file=atmega/ATmegaBOOT_168_atmega328.hex diecimila.menu.cpu.atmega328.build.mcu=atmega328p ## Arduino Duemilanove or Diecimila w/ ATmega168 ## --------------------------------------------- diecimila.menu.cpu.atmega168=ATmega168 diecimila.menu.cpu.atmega168.upload.maximum_size=14336 diecimila.menu.cpu.atmega168.upload.maximum_data_size=1024 diecimila.menu.cpu.atmega168.upload.speed=19200 diecimila.menu.cpu.atmega168.bootloader.high_fuses=0xdd diecimila.menu.cpu.atmega168.bootloader.extended_fuses=0x00 diecimila.menu.cpu.atmega168.bootloader.file=atmega/ATmegaBOOT_168_diecimila.hex diecimila.menu.cpu.atmega168.build.mcu=atmega168 ############################################################## I have replaced the line containing: diecimila.menu.cpu.atmega328.bootloader.extended_fuses=0x05 with: diecimila.menu.cpu.atmega328.bootloader.extended_fuses=0xFD Everything is ok now. I can install boot loader on an ATMEGA328P (with an usbasp programmer), and I can install sketchs after that (via usb serial). I don't know if it's the best way to solve the problem, but it works. Hope this will help you, if not already solved.