You have no swap!
~$ free -h
total used free shared buff/cache available
Mem: 2.9Gi 671Mi 1.3Gi 141Mi 997Mi 2.0Gi
Swap: 0B 0B 0B
Lets create a /swapfile...
Note: Incorrect use of the dd command can cause data loss. Suggest copy/paste.
In the terminal...
Note: instructions reduced from a 4G, to a 1G /swapfile, due to disk space issues.
sudo swapoff -a # turn off swap
sudo rm -i /swapfile # remove old /swapfile
sudo dd if=/dev/zero of=/swapfile bs=1M count=1024
sudo chmod 600 /swapfile # set proper file protections
sudo mkswap /swapfile # init /swapfile
sudo swapon /swapfile # turn on swap
free -h # confirm 3G RAM and 1G swap
Add this /swapfile line at the end of /etc/fstab... and confirm no other “swap” lines...
To edit, use sudo -H gedit /etc/fstab or sudo pico /etc/fstab
/swapfile none swap sw 0 0
reboot # reboot and verify operation