Uploading Problems with the Arduino Robot: butterfly_recv(): programmer is not responding - arduino

Question

I started working with the Arduino Robot Control Board a few days ago. I did a few tutorials and everything was fine. I could perfectly upload my programs using the Arduino IDE.
Today, I was working on a project and already did uploading, testing, adjusting, uploading again,... I pressed the Upload button and nothing happened and I got the following error message (with verbose output enabled):
Der Sketch verwendet 14960 Bytes (52%) des Programmspeicherplatzes. Das Maximum sind 28672 Bytes.
Globale Variablen verwenden 1539 Bytes (60%) des dynamischen Speichers, 1021 Bytes für lokale Variablen verbleiben. Das Maximum sind 2560 Bytes.
Erzwinge Reset durch öffnen/schließen mit 1200 bps auf dem Port /dev/ttyACM1
Beim Hochladen des Sketches ist ein Fehler aufgetreten
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
PORTS {/dev/ttyACM1, } / {/dev/ttyACM1, } => {}
Uploading using selected port: /dev/ttyACM1
/home/lukas/Dokumente/Arduino/arduino-1.8.5/hardware/tools/avr/bin/avrdude -C/home/lukas/Dokumente/Arduino/arduino-1.8.5/hardware/tools/avr/etc/avrdude.conf -v -patmega32u4 -cavr109 -P/dev/ttyACM1 -b57600 -D -Uflash:w:/tmp/arduino_build_7255/Interrupts.ino.hex:i
avrdude: Version 6.3, compiled on Jan 17 2017 at 06:01:25
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "/home/lukas/Dokumente/Arduino/arduino-1.8.5/hardware/tools/avr/etc/avrdude.conf"
User configuration file is "/home/lukas/.avrduderc"
User configuration file does not exist or is not a regular file, skipping
Using Port : /dev/ttyACM1
Using Programmer : avr109
Overriding Baud Rate : 57600
AVR Part : ATmega32U4
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PA0
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
eeprom 65 20 4 0 no 1024 4 0 9000 9000 0x00 0x00
flash 65 6 128 0 yes 32768 128 256 4500 4500 0x00 0x00
lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
Programmer Type : butterfly
Description : Atmel AppNote AVR109 Boot Loader
Connecting to programmer: .avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
Found programmer: Id = "�"; type = �
Software Version = Y.�; Hardware Version = .
avrdude: butterfly_recv(): programmer is not responding
avrdude: butterfly_recv(): programmer is not responding
avrdude: error: buffered memory access not supported. Maybe it isn't
a butterfly/AVR109 but a AVR910 device?
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
this check.
avrdude: butterfly_recv(): programmer is not responding
avrdude: error: programmer did not respond to command: leave prog mode
avrdude: butterfly_recv(): programmer is not responding
avrdude: error: programmer did not respond to command: exit bootloader
I did check the connection, made sure, that the USB cable is not broken. I actually can use the IDE to upload programs to the lower Motor Board, so it's not the IDE's fault, I assume. But as I am fairly new to the Arduino World, I am quite clueless now.
I read a lot of forum posts, but I couldn't find a working solution. Similiar problems seem to happen to others as well, but for other Arduino platforms. Those answers did not solve my problem, including the Arduino Forum itself.
I am currently on Lubuntu 16.04.3 LTS or Windows 10. The same problem is on both OSes.