@aen I had a different experience. This worked for me: >>> import sqnsupgrade >>> sqnsupgrade.info() <<< Welcome to the SQN3330 firmware updater [1.2.6] >>> >>> FiPy with firmware version 1.20.0.rc13 Your modem is in application mode. Here is the current version: UE5.0.0.0d LR5.1.1.0-46470 Then on the terminal: >>> sqnsupgrade.run('/dev/ttyACM0', 'NB1-41019.dup') <<< Welcome to the SQN3330 firmware updater [1.2.5] >>> Firmware file is too big to load via FFF method. Using ON_THE_FLY Attempting AT wakeup... Session opened: version 1, max transfer 8192 bytes Sending 5835531 bytes: [########################################] 100% Waiting for modem to finish the update... <<<=== DO NOT DISCONNECT POWER ===>>> Resetting............................. Your modem has been successfully updated. Here is the current firmware version: UE6.0.0.0 LR6.0.0.0-41019 When I tried your method (to upgrade) the result was an error: Upgrade failed with result failure[diffUpgrade,239] Patch didn't apply! So I figured I'd just upload the final image rather than a diff as the factory shipped firmware appeared to be some unknown number (46470) The documentation on all this is convoluted when its probably quite simple. Philip

I came across this "bytesdfu-util: Error sending completion packet" error today when attempting to upgrade a Pycom Expansionboard 3.1 connected to an Ubuntu 18.04 LTS. Running ls -la /dev showed that the serialport had restricted access, so a quick fix was: sudoedit /etc/udev/rules.d/50-myusb.rules and insert the following: KERNEL=="ttyUSB[0-9]*",MODE="0666" KERNEL=="ttyACM[0-9]*",MODE="0666" then sudo reboot After rebooting the firmware upgrade worked great (holding the s1 button when connecting the USB-cable; releasing s1 after one second; then running dfu-util within a few seconds). sudo su - dfu-util -D /home/user/Download/expansion31_0.0.11.dfu