Virtualbox on Ubuntu Host-System
General error since Ubuntu 24.04.3 LTS
VirtualBox can't operate in VMX root mode. Please disable the KVM kernel extension, recompile your kernel and reboot (VERR_VMX_IN_VMX_ROOT_MODE).
Solution ...
Before starting the VM: sudo modprobe -r kvm_intel
After closing the VM: sudo modprobe kvm_intel
(For AMD: kvm_amd instead of kvm_intel)
Virtualbox for Windows Guest-Systems
Instructions on Ubuntu to consider
Software and Extensionpack: https://www.virtualbox.org/wiki/Downloads
Host-Extension access (for USB and shared folder):
sudo usermod -aG vboxusers $USER
Error: If Kernel-Modules can not be created:
1. sudo apt install dkms build-essential
2. execute /sbin/vboxconfig
Tip: Instead of Mousepad use Featherpad as Text-Editor in the Host-System to avoid opening-errors on
the Guest-System when using shared folders and install Notepad++ on the Guest-System for
proper display-format when displaying Text-Files created on Ubuntu.
Virtualbox for Ubuntu Guest-Systems
sudo apt install build-essentials
sudo apt install linux-headers-$(uname -r)
sudo apt install dkms * not required (dkms only for Distro-Update)
If you ignored the username and password fields in the VirtualBox "Unattended
Install" dialog, then following account will be created:
Username: vboxuser
Password: changeme
Host-Extension access (for USB and shared folder):
sudo ./VBoxLinuxAdditions.run
sudo usermod -aG vboxsf USERNAME * Replace "USERNAME" with "vboxuser" and restart OS