Edit:
sudo nano /etc/apt/sources.list.d/virtualbox.list
and change:
deb https://download.virtualbox.org/virtualbox/debian bionic contrib
for
deb [arch=amd64] https://download.virtualbox.org/virtualbox/debian bionic contrib
Or open terminal an execute the following command:
echo "deb [arch=amd64] https://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
Or run this bash script to install virtualbox and its dependencies from Oracle repository (tested in Ubuntu 18.04/20.04):
chmod +x VboxInstall.sh && ./VboxInstall.sh
#!/bin/bash
# Install Virtualbox from Oracle Repository
echo "deb [arch=amd64] http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
sudo su -c 'wget -q -O- https://www.virtualbox.org/download/oracle_vbox.asc | apt-key add -'
sudo su -c 'wget -q -O- http://download.virtualbox.org/virtualbox/debian/oracle_vbox_2016.asc | apt-key add -'
sudo apt-get update
sudo apt-get -y install linux-headers-$(uname -r) build-essential gcc make perl dkms bridge-utils
sudo apt-get -y install virtualbox-6.1
sudo dpkg --configure -a && sudo apt-get -f -y install
export VBOX_VER=`VBoxManage --version | awk -Fr '{print $1}'`
wget -c http://download.virtualbox.org/virtualbox/$VBOX_VER/Oracle_VM_VirtualBox_Extension_Pack-$VBOX_VER.vbox-extpack
sudo VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-$VBOX_VER.vbox-extpack
sudo usermod -a -G vboxusers $USER
sudo update-grub
sudo /sbin/vboxconfig
Important: If you have a previous versions of virtualbox installed (from Ubuntu or Oracle repositories), remove it and backup your VM and config before running script
# Purge Virtualbox
sudo vboxmanage list runningvms | sed -r 's/.*\{(.*)\}/\1/' | sudo xargs -L1 -I {} VBoxManage controlvm {} savestate
sudo VBoxManage extpack uninstall "Oracle VM VirtualBox Extension Pack"
sudo systemctl stop vboxweb-service.service
# using wildcard may not work on some linux systems, and you have to specify the version to remove:
sudo apt-get -y autoremove --purge virtualbox*
sudo rm -rf /etc/vbox /usr/lib/virtualbox /opt/VirtualBox /etc/apt/sources.list.d/virtualbox.list
# optional:
# sudo rm -rf ~/.config/VirtualBox
Source: Virtualbox kernel service is not running