Lab 3.2 Unable to start container.

Lab 3.2. I'm using the LF pre-built Ubuntu 18.04 on VMware Workstation 15 Player.
Everthing seems to work fine until I try to start the container. I'm afraid the error messages don't mean much to me. Any guidance here would be appreciated. Thanks. ldt

student@ubuntu:~$ cat /etc/subuid
student:100000:65536
student@ubuntu:~$ cat /etc/subgid
student:100000:65536
student@ubuntu:~$ cat /etc/lxc/lxc-usernet
# USERNAME TYPE BRIDGE COUNT
student veth lxcbr0 10
student@ubuntu:~$ cat ~/.config/lxc/default.conf 
lxc.net.0.type = veth
lxc.net.0.link = lxcbr0
lxc.net.0.flags = up
lxc.net.0.hwaddr = 00:16:3e:xx:xx:xx
lxc.idmap = u 0 100000 65536
lxc.idmap = g 0 100000 65536
student@ubuntu:~$ 

...

Distribution: 
ubuntu
Release: 
xenial
Architecture: 
amd64
 
Downloading the image index
Downloading the rootfs
Downloading the metadata
The image cache is now ready
Unpacking the rootfs
 
---
You just created an Ubuntu xenial amd64 (20200914_07:42) container.
 
To enable SSH, run: apt install openssh-server
No default root or user password are set by LXC.

student@ubuntu:~$ lxc-start -n unpriv-cont-user -d
lxc-start: unpriv-cont-user: lxccontainer.c: wait_on_daemonized_start: 842 Received container state "ABORTING" instead of "RUNNING"
lxc-start: unpriv-cont-user: tools/lxc_start.c: main: 330 The container failed to start
lxc-start: unpriv-cont-user: tools/lxc_start.c: main: 333 To get more details, run the container in foreground mode
lxc-start: unpriv-cont-user: tools/lxc_start.c: main: 336 Additional information can be obtained by setting the --logfile and --logpriority options

student@ubuntu:~$ lxc-start -n unpriv-cont-user -F --logfile=/tmp/logfile --logpriority=WARN
lxc-start: unpriv-cont-user: network.c: lxc_create_network_unpriv_exec: 2178 lxc-user-nic failed to configure requested network: cmd/lxc_user_nic.c: 576: create_nic: Error attaching veth0YJFD5 to lxcbr0
                                     lxc-start: unpriv-cont-user: start.c: lxc_spawn: 1765 Failed to create the configured network
                                                                                                                                  lxc-start: unpriv-cont-user: start.c: __lxc_start: 1939 Failed to spawn container "unpriv-cont-user"
                                                                 lxc-start: unpriv-cont-user: tools/lxc_start.c: main: 330 The container failed to start
lxc-start: unpriv-cont-user: tools/lxc_start.c: main: 336 Additional information can be obtained by setting the --logfile and --logpriority options
student@ubuntu:~$ cat /tmp/logfile
lxc-start unpriv-cont-user 20200914174644.524 WARN     start - start.c:lxc_spawn:1746 - Operation not permitted - Failed to allocate new network namespace id
lxc-start unpriv-cont-user 20200914174644.575 ERROR    network - network.c:lxc_create_network_unpriv_exec:2178 - lxc-user-nic failed to configure requested network: cmd/lxc_user_nic.c: 576: create_nic: Error attaching veth0YJFD5 to lxcbr0
lxc-start unpriv-cont-user 20200914174644.575 ERROR    start - start.c:lxc_spawn:1765 - Failed to create the configured network
lxc-start unpriv-cont-user 20200914174644.575 ERROR    start - start.c:__lxc_start:1939 - Failed to spawn container "unpriv-cont-user"
lxc-start unpriv-cont-user 20200914174645.124 ERROR    lxc_start - tools/lxc_start.c:main:330 - The container failed to start
lxc-start unpriv-cont-user 20200914174645.124 ERROR    lxc_start - tools/lxc_start.c:main:336 - Additional information can be obtained by setting the --logfile and --logpriority options
student@ubuntu:~$