Virtualization Added 11 February 2026

QEMU/KVM: /dev/kvm not available

KVM kernel module is not loaded or the user doesn't have permission to access /dev/kvm. Hardware virtualization may be disabled.

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

Quick fix

# Check KVM support
kvm-ok
# Load KVM module
sudo modprobe kvm_intel  # or kvm_amd
# Fix permissions
sudo usermod -aG kvm $USER
# Check if nested virtualization is needed
cat /sys/module/kvm_intel/parameters/nested

How to diagnose Virtualization errors

Virtualisation errors are usually about hardware virtualisation access: either it is disabled in firmware, or another hypervisor already holds it. On Windows, Hyper-V, WSL 2, Docker Desktop, Credential Guard and memory integrity all claim the virtualisation extensions, and VirtualBox or VMware then fails with a message that mentions VT-x but not the actual conflict.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

Confirm virtualisation is enabled at the CPU level: grep -E 'vmx|svm' /proc/cpuinfo on Linux, or the Performance tab of Task Manager on Windows.
On Windows, check what else is using the hypervisor: bcdedit /enum | findstr hypervisorlaunchtype and whether Hyper-V, WSL 2 or Core Isolation are enabled.
On Linux, check /dev/kvm exists and that your user is in the kvm group; nested virtualisation must be enabled explicitly on cloud VMs.
Match guest additions and tools versions to the hypervisor version: mismatches cause shared folders, clipboard and display problems that look like guest OS bugs.
For WSL, run wsl --status and wsl --update; most WSL 2 errors are a stale kernel or a disabled Virtual Machine Platform feature.

Tools worth reaching for

grep -E 'vmx|svm' /proc/cpuinfo
wsl --status
bcdedit /enum
ls -l /dev/kvm
systemctl status libvirtd

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

linux-kvm.org

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This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.