Hello, This is not a bug and therefor I want to refrain from posting at the repository issues list. I'm running dfu-util to flash firmware to the GIGA board to start with MicroPython exercises. Here is the output: $ /usr/bin/dfu-util -w -a 0 -d 2341:0366 -D GIGAR1_MP_FW.dfu dfu-util 0.11 Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc. Copyright 2010-2021 Tormod Volden and Stefan Schmidt This program is Free Software and has ABSOLUTELY NO WARRANTY Please report bugs to http://sourceforge.net/p/dfu-util/tickets/ Waiting for device, exit with ctrl-C ^C The ports on the desktop are: from ttyACM0 to ttyACM5 from ttyUSB0 to ttyUSB3 The GIGA is connected through ttyACM4 libusb version 1.0.26 (11724) I used dfu-util successfully (thanks to Tormod's advice) by setting the configuration rules for the USB port. Naturally, the port assignments for the GIGA board change in my environment but the Arduino IDE 2.4 correctly detects the right port for the board. Do I have to set the port (in my environment) while using dfu-util to flash the firmware? There is a port parameter but I don't know the correct way to specify the port. Also, I couldn't use the -l parameter to gain insight on the connected devices. Also, some clarification on the -a parameter would help my understanding. Thanks. Regards.