libvirt/docs/kbase/failed_connection_after_install.rst

Libvirt does not work after installation

TL;DR

Most probably you want to start a virtqemud socket:

# systemctl start virtqemud.socket

If you are unsure whether to do this, please read the rest of this document.

Symptom

After installing libvirt or a virt tool that uses libvirt, commands do not work when run as root:

# virsh list
error: failed to connect to the hypervisor
error: Operation not supported: Cannot use direct socket mode if no URI is set.
For more information see https://libvirt.org/kbase/failed_connection_after_install.html

Root cause

Distribution guidelines and/or configurations may discourage or prohibit starting services as part of a package installation. And because libvirt cannot know where you might want to connect it cannot start it on its own.

Solution

After installing libvirt you may need to start a particular libvirt daemon on the local machine, set a (default) URI to connect to or, alternatively, rebooting the machine might work.

If you are trying to connect to a remote libvirt daemon you need to specify a connection URI.

If you are trying to control a local hypervisor, then the solution depends on various factors. You should know:

• what hypervisor driver you want to connect to, whether it is virtqemud for QEMU, virtchd for Cloud Hypervisor, etc. and
• how to start a service or socket (in case of systemd) on you system.

Example of the most common solution, trying to use QEMU/KVM on Linux with systemd as an init system, is:

# systemctl start virtqemud.socket

also provided on the top of the page.