systemctl restart systemd-udevd; udevadm trigger; udevadm settle

lxc-start -lDEBUG -o /tmp/112.log -F -n 112

# open  /etc/pve/qemu-server/101.conf and add the following parameter at the end of file
serial0: socket

qm set 101 -serial0 socket

dmesg | grep ttyS
[    0.457814] 00:0a: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

# in /etc/default/grub change the GRUB_CMDLINE_LINUX parameter to
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8"

update-grub (debian)
grub2-mkconfig -o /boot/grub2/grub.cfg (rhel)

systemctl enable --now serial-getty@ttyS0.service

qm terminal <VMiD>