Comment # 45 on bug 1183247 from Till D���rges

FWIW:

My host (including LXC containers) was working fine with Leap 15.3.

After 'zypper dup' to 15.4 the LXC containers weren't starting anymore showing
the error

  PID ... does not belong to any known machine

Adding systemd.unified_cgroup_hierarchy=1 to the kernel cmdline didn't help.
The error changed to

  internal error: Unable to find 'memory' cgroups controller mount


Downgrading to the packages from Leap 15.3 does give me working LXC containers:

  # add 15.3 repos
  http://download.opensuse.org/distribution/leap/15.3/repo/oss/
  http://download.opensuse.org/update/leap/15.3/sle/
  http://download.opensuse.org/update/leap/15.3/oss

  # downgrade
  zypper install --oldpackage libvirt-daemon-driver-lxc-7.1.0-150300.6.35.2
libvirt-7.1.0-150300.6.35.2
  [...]
  The following 52 packages are going to be downgraded:
    kexec-tools libvirt libvirt-client libvirt-daemon
libvirt-daemon-config-network libvirt-daemon-config-nwfilter
libvirt-daemon-driver-interface libvirt-daemon-driver-libxl
libvirt-daemon-driver-lxc libvirt-daemon-driver-network
    libvirt-daemon-driver-nodedev libvirt-daemon-driver-nwfilter
libvirt-daemon-driver-qemu libvirt-daemon-driver-secret
libvirt-daemon-driver-storage libvirt-daemon-driver-storage-core
libvirt-daemon-driver-storage-disk
    libvirt-daemon-driver-storage-gluster libvirt-daemon-driver-storage-iscsi
libvirt-daemon-driver-storage-iscsi-direct
libvirt-daemon-driver-storage-logical libvirt-daemon-driver-storage-mpath
libvirt-daemon-driver-storage-rbd
    libvirt-daemon-driver-storage-scsi libvirt-daemon-lxc libvirt-libs lxd
lxd-bash-completion python3-libvirt-python qemu qemu-audio-spice
qemu-block-curl qemu-block-nfs qemu-block-rbd qemu-chardev-baum
qemu-chardev-spice
    qemu-hw-display-qxl qemu-hw-display-virtio-gpu
qemu-hw-display-virtio-gpu-pci qemu-hw-display-virtio-vga
qemu-hw-s390x-virtio-gpu-ccw qemu-hw-usb-redirect qemu-hw-usb-smartcard
qemu-kvm qemu-tools qemu-ui-curses qemu-ui-gtk
    qemu-ui-opengl qemu-ui-spice-app qemu-ui-spice-core qemu-x86 xen-libs

  The following 3 NEW packages are going to be installed:
    libbrlapi0_7 libvirglrenderer0 libvirt-bash-completion

  The following 3 packages are going to be REMOVED:
    qemu-accel-qtest qemu-accel-tcg-x86 qemu-hw-usb-host
  [...]

  # lock versions
  zypper addlock libvirt-daemon-driver-lxc

  # remove 15.3 repos