Connect Nokia 8 with Ubuntu 18.04 for filetransfer
Install packages for Media Transfer Protocol
sudo apt-get install mtpfs mtp-tools
Check, if your machine has the file /etc/udev/rules.d/69-libmtp.rules.
sudo less /etc/udev/rules.d/69-libmtp.rules
If not copy it from /lib/udev/rules.d/69-libmtp.rules.
sudo cp /lib/udev/rules.d/69-libmtp.rules /etc/udev/rules.d/69-libmtp.rules
Now open the copied file with root rights and add the following line
# Nokia 8
ATTR{idVendor}=="2e04", ATTR{idProduct}=="c025", SYMLINK+="libmtp-%k", MODE="660", GROUP="disk", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
I had at the end the following lines in my file
# Parrot Bebop Drone
ATTR{idVendor}=="19cf", ATTR{idProduct}=="5038", SYMLINK+="libmtp-%k", MODE="660", GROUP="audio", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
# Isabella Her Prototype
ATTR{idVendor}=="0b20", ATTR{idProduct}=="ddee", SYMLINK+="libmtp-%k", MODE="660", GROUP="audio", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
# Nokia 8
ATTR{idVendor}=="2e04", ATTR{idProduct}=="c025", SYMLINK+="libmtp-%k", MODE="660", GROUP="disk", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
# Autoprobe vendor-specific, communication and PTP devices
ENV{ID_MTP_DEVICE}!="1", ENV{MTP_NO_PROBE}!="1", ENV{COLOR_MEASUREMENT_DEVICE}!="1", ENV{libsane_matched}!="yes", ATTR{bDeviceClass}=="00|02|06|ef|ff", PROGRAM="mtp-probe /sys$env{DEVPATH} $attr{busnum} $attr{devnum}", RESULT=="1", SYMLINK+="libmtp-%k", MODE="660", GROUP="audio", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"
LABEL="libmtp_rules_end"
Information, how to setup udev can you find here: https://wiki.ubuntuusers.de/MTP/