libvirtd.service: Referenced but unset environment variable evaluates to an empty string: LIBVIRTD_ARGS

[Sundar Nagarajan]

The package is from package libvirt-daemon-system but form variable above gives error '"libvirt-daemon-system" does not exist in Ubuntu'

apt-cache show libvirt-daemon-system
Package: libvirt-daemon-system
Architecture: amd64
Version: 10.0.0-2ubuntu8.6
Priority: optional
Section: admin
Source: libvirt
Origin: Ubuntu
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Debian Libvirt Maintainers <email address hidden>
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Installed-Size: 335
Depends: adduser, gettext-base, iptables | firewalld, libvirt-clients (= 10.0.0-2ubuntu8.6), libvirt-daemon (= 10.0.0-2ubuntu8.6), libvirt-daemon-config-network (= 10.0.0-2ubuntu8.6), libvirt-daemon-config-nwfilter (= 10.0.0-2ubuntu8.6), libvirt-daemon-system-systemd (= 10.0.0-2ubuntu8.6) | libvirt-daemon-system-sysv (= 10.0.0-2ubuntu8.6), libvirt0 (<< 10.0.0-2ubuntu8.6.1~), libvirt0 (>= 10.0.0-2ubuntu8.6), logrotate, polkitd (>= 121+compat0.1-2), debconf (>= 0.5) | debconf-2.0
Recommends: dmidecode, dnsmasq-base, iproute2, mdevctl, parted
Suggests: apparmor, auditd, nfs-common, open-iscsi, pm-utils, systemd, systemtap, zfsutils
Filename: pool/main/libv/libvirt/libvirt-daemon-system_10.0.0-2ubuntu8.6_amd64.deb
Size: 49536
MD5sum: 3157c752c6fb6584891b7b962f386c1b
SHA1: 6246f94344067474b1953a699323ec40f9df0b3c
SHA256: e9e6007462ea8272fa18105ab7c1b6a52cbc830ded5ad5df5f4133ef1e94259f
SHA512: b3b93731aafb9b32274c1a2ad5c6360a8965eeb71e5f97fde73b295f87ae54691f8e3c381398028e4356b01df9520ced84ccc93b791070b57527e6decd796055
Homepage: https://libvirt.org/
Description-en: Libvirt daemon configuration files
 Libvirt is a C toolkit to interact with the virtualization capabilities
 of recent versions of Linux (and other OSes). The library aims at providing
 a long term stable C API for different virtualization mechanisms. It currently
 supports QEMU, KVM, XEN, OpenVZ, LXC, and VirtualBox.
 .
 This package contains the configuration files to run the libvirt daemon as a
 system service.
Description-md5: da7cc4d36dd1ad0862cb38e713552e24

Output of lsb_release -rd
No LSB modules are available.
Description: Ubuntu 24.04.2 LTS
Release: 24.04

Output of apt-cache policy libvirt-daemon-system
libvirt-daemon-system:
  Installed: 10.0.0-2ubuntu8.6
  Candidate: 10.0.0-2ubuntu8.6
  Version table:
 *** 10.0.0-2ubuntu8.6 500
        500 http://us.archive.ubuntu.com/ubuntu noble-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     10.0.0-2ubuntu8.2 500
        500 http://security.ubuntu.com/ubuntu noble-security/main amd64 Packages
     10.0.0-2ubuntu8 500
        500 http://us.archive.ubuntu.com/ubuntu noble/main amd64 Packages

The following WARNING (not error) appears in journalctl log:

libvirtd.service: Referenced but unset environment variable evaluates to an empty string: LIBVIRTD_ARGS

Fix:

Add following lines to /etc/default/libvirtd:
LIBVIRTD_ARGS=""