1. Open the file /etc/apt/sources.list
2. Add the following lines:
deb http://archive.ubuntu.com/ubuntu bionic multiverse
deb http://archive.ubuntu.com/ubuntu bionic-security multiverse
deb http://archive.ubuntu.com/ubuntu bionic-updates multiverse
deb http://archive.ubuntu.com/ubuntu bionic universe
deb http://archive.ubuntu.com/ubuntu bionic-security universe
deb http://archive.ubuntu.com/ubuntu bionic-updates universe
3. Save the file.
4. Launch the following command to update the packages
sudo apt update