First check if group already exist, if not create it

sudo getent group | grep libvirt

If it doesn’t exist, add it as a system group.

sudo groupadd --system libvirt

Add your user account to the group and log onto that group (without logging off and back onto the machine)

sudo usermod -a -G libvirt $(whoami)
newgrp libvirt

Verify that user is added to libvirt group.

$ id $(whoami)
uid=1000(myusername) gid=1000(myusername) groups=1000(myusername),10(wheel),982(libvirt)

Open the file /etc/libvirt/libvirtd.conf for editing.

sudo vim /etc/libvirt/libvirtd.conf

Set the UNIX domain socket group ownership to libvirt – by removing the # at the begining of the following line

unix_sock_group = "libvirt"

Set the UNIX socket permissions for the R/W socket – by removing the # at the begining of the following line

unix_sock_rw_perms = "0770"

Restart libvirt daemon after making the change.

sudo systemctl restart libvirtd.service

Check service status.

$ systemctl status libvirtd.service    
 ● libvirtd.service - Virtualization daemon
    Loaded: loaded (/usr/lib/systemd/system/libvirtd.service; enabled; vendor preset: disabled)
    Active: active (running) since Fri 2019-04-19 08:48:13 EAT; 1h 16min ago
      Docs: man:libvirtd(8)
            https://libvirt.org
  Main PID: 31709 (libvirtd)
     Tasks: 26 (limit: 32768)
    Memory: 64.7M
    CGroup: /system.slice/libvirtd.service
            ├─  754 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leases>
            ├─  755 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leases>
            ├─  777 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/docker-machines.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvir>
            ├─  778 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/docker-machines.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvir>
            ├─25924 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/vagrant-libvirt.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvir>
            ├─25925 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/vagrant-libvirt.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvir>
            ├─25959 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/fed290.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leasesh>
            ├─25960 /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/fed290.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leasesh>
            └─31709 /usr/bin/libvirtd

Start Virtual Machine Manager from the command line or your Start menu.

$ virt-manager

You should be able to create a VM without getting a permission error.

Tested on Rocky 8, Rocky 9 and Fedora 39